I think it was 'new_world' that question whether there were any historical references prior to 2,500 ago ... here is an orthodox overview. Inexhaustive but with a special reference to Bharat. Note later reference to Sanskrit well before the time of Shankaracharya and Indian population 2000 BC. Baba says that each religious founder brings their own language and Shankaracharya brought Sanskrit.
I once met some Christians that told me with a straight face and complete faith that the bone of dinosaurs found in 100,000 of years old rocks were put there by Satan to deceive the non-believers into thinking the Biblical story of creation (which is a 7 Days and little older that 5,000 years ...) was wrong.
The BK version that I have been told by senior BKs is that at the end of the Silver Age beginning of Copper Age (2,500 years ago) there were natural disasters and then possible wars that destroyed the Silver Aged palaces and technology and that this is remembered in the Atlantis story. Atlantis was the Silver Aged world in Bharat. He told me that when the nuclear power stations that powered the deity world was destroyed, the radioactivity from them caused the carbon record and scientific calculations to be made worthless.
Having said that, there are a number of scientific anomalies in the fossil record that need a proper scientist to explain.
Dateline according to BC - (the Birth of Christ), e.g. 500 'ASA' (After the Silver Age)
I once met some Christians that told me with a straight face and complete faith that the bone of dinosaurs found in 100,000 of years old rocks were put there by Satan to deceive the non-believers into thinking the Biblical story of creation (which is a 7 Days and little older that 5,000 years ...) was wrong.
The BK version that I have been told by senior BKs is that at the end of the Silver Age beginning of Copper Age (2,500 years ago) there were natural disasters and then possible wars that destroyed the Silver Aged palaces and technology and that this is remembered in the Atlantis story. Atlantis was the Silver Aged world in Bharat. He told me that when the nuclear power stations that powered the deity world was destroyed, the radioactivity from them caused the carbon record and scientific calculations to be made worthless.
Having said that, there are a number of scientific anomalies in the fossil record that need a proper scientist to explain.
Dateline according to BC - (the Birth of Christ), e.g. 500 'ASA' (After the Silver Age)
- 2,000,000 BC - Stone artifacts are made and used by hominids in North India, an area rich in animal species, including the elephant.
500,000 BC - Stone hand axes and other tools are used in North India.
470,000 BC - India's hominids are active in Tamil Nadu and Punjab.
400,000 BC - Soan culture in India is using primitive chopping tools.
360,000 BC - Fire is first controlled by homo erectus in China.
300,000 BC - Homo sapiens roams the Earth, from Africa to Asia.
100,000 BC - Homo sapiens sapiens with 20th-century man's brain size (1,450 cc) are in East Africa. Populations separate.
75,000 BC - Last Ice Age begins. Human population estimated at 1.7 million.
60,000 BC - According to genetic scientist Spencer Wells' research, televised by National Geographic, early man's first wave of migration from Africa occurred at this time to India, evidenced by the genetic makeup of Tamil Nadu's modern-day Kallar community, who are related to the Australian aborigines.
50,000 BC - Genetic research by Richard Villems of the Estonian Biocentre concludes that the maternal lineages of modern-day India's populations are largely unique to India, and on the order of 50,000 years old. As a result, Villems said, "I think that the Aryan Invasion theory in its classic form is dead."
45,000 BC - Seafaring migrations from S.E. Asia settle Indonesian Islands and Australia.
40,000 BC - Hunter-gatherers in Central India are living in painted rock shelters. Similar groups in Punjab camp at sites protected by windbreaks. Cave paintings found in 2002 in Banda depict a hunter riding a horse in a group hunting scene.
30,000 BC - American Indians spread throughout the Americas.
10,000 BC - Last Ice Age ends after 65,000 years; earliest signs of agriculture. World population is 4 million; India, 100,000.
10,000 BC - Taittiriya Brahmana 3.1.2 refers to Purvabhadrapada nakshatra's rising due east, a phenomenon occurring at this date (Dr. B.G. Siddharth of the Birla Science Institute), indicating earliest known dating of the sacred Veda.
10,000 BC - Vedic culture, the essence of humanity's eternal wisdom, Sanatana Dharma, lives in Himalayas at end of Ice Age.
9000 BC - Old Europe, Anatolia and Minoan Crete display a Goddess-centered culture reflecting a matriarchial order.
8500 BC - Taittiriya Samhita 6.5.3 places Pleiades asterism at winter solstice, suggesting the antiquity of this Veda.
7500 BC - Excavations at Neveli Cori in Turkey reveal advanced civilization with developed architecture. B.G. Siddharth believes this was a Vedic culture.
7200 BC - War of the Ten Kings is fought (dating by S.D. Kulkarni).
7000 BC - Proto-Vedic period ends. Early Vedic period begins.
7000 BC - Time of Manu Vaivasvata, "Father of Mankind," of Sarasvati-Drishadvati area (also said to be a South Indian monarch who sailed to the Himalayas during a great flood).
7000 BC - Early evidence of modern horses in the Ganga basin (Frawley).
7000 BC - Indus-Sarasvati area residents of Mehergarh grow barley, raise sheep and goats, store grain, entomb their dead and construct buildings of sun-baked mud bricks. (S.D. Kulkarni asserts such refinements had existed for ages, though archeology reaches only to this period.)
6776 BC - Start of Hindu king's lists according to Greek references that give Hindus 150 kings and a history of 6,400 years before 300 BC.
6500 BC - Rig Veda verses say winter solstice begins in Aries (according to D. Frawley), giving antiquity of this section of the Vedas.
6000 BC - Early sites on the Sarasvati River, then India's largest, flowing West of Delhi into the Rann of Kutch; Rajasthan is a fertile region with much grassland, as described in the Rig Veda. The culture, based upon barley (yava), copper (ayas) and cattle, also reflects that of the Rig Veda.
5500 BC - Date of astrological observations associated with ancient events later mentioned in the Puranas (Alain Danielou).
5500 BC - Mehergarh villagers make baked pottery and thousands of small, clay of female figurines (interpreted to be earliest signs of Shakti worship), and are involved in long-distance trade in precious stones and sea shells.
5000 BC - World population, 5 million; doubles every 1,000 years.
5000 BC - Beginnings of Indus-Sarasvati civilizations of Harappa and Mohenjo-daro. Date derived by considering excavated archeological sites 45 feet deep. Brick fire altars exist in many houses, suggesting Vedic fire rites. Earliest signs of Siva. This mature culture lasts 3,000 years, ending around -1700.
5000 BC - Rice is harvested in China, with grains found in baked bricks. But its cultivation originated in Eastern India.
4300 BC - Traditional date for Lord Rama's time (Kulkarni's date is -5500; see also-2040, and latest dating at -500).
4004 BC - Archbishop Usher's (17th century) supposed date of the creation of the world, based on genealogies in the Old Testament.
4000 BC - Excavations from this period at Sumerian sites of Kish and Elamite Susa reveal presence of Indian imports.
4000 BC - India's population is 1 million.
3928 BC - July 25th: the earliest eclipse mentioned in the Rig Veda (according to Indian researcher Dr. Sri P.C. Sengupta).
3761 BC - The year of world creation in the Jewish religious calendar.
3200 BC - In India, a special guild of Hindu astronomers (nakshatra darshas) record in Vedic texts citations of full and new moon at winter and summer solstices and spring and fall equinoxes with reference to 27 fixed stars (nakshatras) spaced nearly equally on the moon's ecliptic (visual path across the sky). The precession of the equinoxes (caused by the mutation of the Earth's axis of rotation) makes the nakshatras appear to drift at a constant rate along a predictable course over a 25,000-year cycle. Such observations enable specialists to calculate backwards to determine the date the indicated position of moon, sun and nakshatra occurred.
3139 BC - Reference to vernal equinox in Rohini (middle of Taurus) from some Brahmanas, as noted by B.G. Tilak, Indian scholar and patriot. Now preferred date of Mahabharata war and life of Lord Krishna (see also -1424).
3102 BC - Beginning of Kali Yuga (Kali Era) in Hindu time reckoning.
3100 BC - Early Vedic period ends, late Vedic period begins.
3100 BC - Indian culture in Afghanistan and parts of Central Asia.
3100 BC - Aryans inhabit Iran, Iraq and Western Indus-Sarasvati Valley frontier. [Frawley describes Aryans as "a culture of spiritual knowledge." He and many Indian scholars believe 1) the Land of Seven Rivers (Sapta Sindhu) cited in the Rig Veda refers to India only, 2) the people of Indus-Sarasvati valleys and those of Rig Veda are the same, and 3) there was no Aryan invasion. Others claim the Indus-Sarasvati people were Dravidians who moved out or were displaced by incoming Aryans.]
3000 BC - Weaving in Europe, Near East and Indus-Sarasvati Valley is primarily coiled basketry, either spiraled or sewn.
3000 BC - Evidence of horses in South India.
3000 BC - People of Tehuacan, Mexico, are cultivating maize.
3000 BC - Saiva Agamas are recorded; time of the earliest Tamil Sangam (by traditional dating; see also -500).
2700 BC - Tolkappiyam Tamil grammar is composed (traditional dating; see also -500).
2700 BC - Seals of Indus-Sarasvati Valley indicate Siva worship, represented by Pashupati, Lord of Animals.
2600 BC - Indus-Sarasvati civilization reaches height it sustains until -1700. Spreading from Pakistan to Gujarat, Punjab and Uttar Pradesh, it is the largest of the world's three oldest civilizations, with links to Mesopotamia (possibly Crete), Afghanisthan, Central Asia and Karnataka. Harappa and Mohenjo-daro each have populations of 100,000.
2600 BC - Major portions of the Veda hymns are composed during the reign of Visvamitra I (Dating by S.B. Roy).
2600 BC - Drying up of Drishadvati River of Vedic fame, along with possible shifting of the Yamuna to flow into the Ganga.
2600 BC - First Egyptian Pyramid under construction.
2500 BC - Main period of Indus-Sarasvati cities. Atharva Veda indicates culture relies heavily on rice and cotton, which were first cultivated in India. Ninety percent of sites are along the Sarasvati, the region's agricultural bread basket. Mohenjo-daro is a large peripheral trading center. Rakhigari and Ganweriwala on the Sarasvati are as big as Mohenjo-daro. So is Dholavira in Kutch. Indus-Sarasvati sites have been found as far south as Karnataka's Godavari River and north into Afghanistan on the Amu Darya River.
2500 BC - Reference to vernal equinox in Krittika (Pleiades or early Taurus) from Yajur and Atharva Veda hymns and Brahmanas. This corresponds to Harappan seals that show seven women (the Krittikas) tending a fire.
2350 BC - Sage Gargya (born 2285), 50th in Puranic list of kings and sages, son of Garga, initiates method of reckoning successive centuries in relation to a nakshatra list he records in the Atharva Veda with Krittika as the first star. Equinox occurs at Krittikia Purnima.
2300 BC - Sargon founds Mesopotamian kingdom of Akkad, trades with Indus-Sarasvati Valley cities.
2300 BC - Indo-Europeans in Russia's Ural steppelands develop efficient spoked-wheel Chariot, using 1,000-year-old horse husbandry and freight-cart technology.
2051 BC - Divodasa reigns to - 1961, has contact with Babylon's King Indatu (Babylonian chronology). Dating by S.B. Roy.
2050 BC - Vedic people are settled in Iran (Persia) and Afghanistan.
ca 2040 BC - Prince Rama born at Ayodhya, site of future Rama temple (this and next two dates by S.B. Roy; see also -4000).
2033 BC - Reign of Dasaratha, Father of Lord Rama. King Ravana, villain of the Ramayana, reigns in Sri Lanka.
2000 BC - Indo-Europeans (Celts, Teutons, Slavs, Balts, Hellens, Italics) follow social usages and beliefs that parallel early Vedic patterns.
2000 BC - Possible date of the first formulated Saiva Agamas.
2000 BC - World population: 27 million. India: 5 million or 22 percent. India has roughly one fourth of human race through much of history.
1915 BC - All Madurai Tamil Sangam is held at Thiruparankundram (according to traditional Tamil chronology).
1900 BC - Late Vedic period ends, post Vedic period begins. (Early dating; see also -1000).
1900 BC - Drying up of Sarasvati River, end of Indus-Sarasvati culture, end of the Vedic age. After this, the center of civilization in ancient India relocates from the Sarasvati to the Ganga, along with possible migration of Vedic peoples out of India to the Near East (perhaps giving rise to the Mitanni and Kassites, who worship Vedic Gods). The redirection of the Sutlej into the Indus causes the Indus area to flood. Climate changes make the Sarasvati region too dry for habitation. (Thought lost, its river bed is finally photographed via satellite in the 1990s.)
1728-1686 BC - Hammurabi, famous lawgiver, is king of Babylon.
1500 BC - Egyptians bury their royalty in the Valley of the Kings.
1500 BC - Polynesians migrate throughout Pacific islands.
1500 BC - Proposed date of submergence of the stone port city of Dwarka near Gujarat. Residents use iron and employ a script halfway between Harappan and Brahmi, India's ancient pre-Sanskritic alphabet. [Findings from recent excavations by Dr. S.R. Rao, larger than Mohenjo-daro. Many identify it with the Dwarka of Krishna's time, suggesting possible date of Lord Krishna. Indicates second urbanization phase of India between Indus-Sarasvati sites like Harappa and later cities on the Ganga.]
1500 BC - Indigenous iron technology in Dwarka and Kashmir.
1500 BC - Cinnamon is exported from Kerala to Middle East.
1450 BC - End of Rig Veda Samhita composition.
1450 BC - Early Upanishads are composed during the next few hundred years, also Vedangas and Sutra literature.
1424 BC - Mahabharata War occurs (dated from reference in the Mahabharata citing winter solstice at Dhanishtha, which occurs around this time). Reign of Kaurava king Dhritarashtra and of Pandava king Yudhishthira. Time of Sage Yajnavalkya. (See now-preferred date at -3139. Subash Kak places the battle at -2449. Others give later dates, up to 9th century BC[/b] - E.)
1424 BC - Birth of Parikshit, grandson of Arjuna, and next king.
1350 BC - At Boghaz Koy, Turkey, stone inscription of the treaty with Mitanni lists as divine witnesses the Vedic Deities Mitra, Varuna, Indra and the Nasatyas (Ashvins).
1316 BC - Mahabharata epic poem is composed by Sage Vyasa.
1300 BC - Very early date (by S.B. Roy) for lifetime of Panini, whose Ashtadhyayi systematizes Sanskrit grammar in 4,000 rules. (Western scholars place him at -400 BC[/b] - e, or as late as 300 ce.)
1300 BC - Revisions are made in the materials of Mahabharata and Ramayana through 200 BC[/b] - E. Puranas are edited up until 400 CE. Early smriti literature is composed over next 400 years.
1255 BC - King Suchi of Magadha sets forth Jyotisha Vedanga, dating it by including an astronomical note that summer solstice is in Ashlesha Nakshatra.
1250 BC - Moses leads 600,000 Jews out of Egypt. (Early traditional dating.)
1200 BC - Approximate time of the legendary Greek-Trojan War celebrated in Homer's epic poems, Iliad and Odyssey (ca -750).
1150 BC - Nebuchadnezzar I of Isin, king of Babylon, throws off Elamite domination.
1000 BC - Late Vedic period ends. Post-Vedic period begins. (Later dating, see also -1900).
1000 BC - World population is 50 million, doubling every 500 years.
1000 BC - Jewish king David (reigns to ca -962) rules a united kingdom in present-day Israel and parts of Jordan and Syria.
950 BC - King Hiram of Tyre in Phoenicia, in treaty with Israel's King Solomon (son of David), trades with the port of Ophir (Sanskrit: Supara) near modern Mumbai. Same trade with India goes back to Harappan era.
950 BC - Jewish traders arrive in India in King Solomon's merchant fleet. Later Jewish colonies find India a tolerant home.
950 BC - Breakdown of Sanskrit as a spoken language occurs over the next 200 years.
900 BC - Iron Age in India. Early sporadic use dates from at least 1500 BC[/b] - .
900 BC - Earliest records of the holy city of Varanasi (one of the world's oldest living cities) on the sacred river Ganga.
900 BC - Use of iron supplements bronze in Greece.
850 BC - The Chinese are using the 28-nakshatra zodiac called Shiu, adapted from the Hindu jyotisha system.
800 BC - Later Upanishads are recorded.
800 BC - Later Smriti (secondary Hindu scriptures) are composed, elaborated and developed during next 1,000 years.
776 BC - First Olympic Games are held and documented in Greece.
750 BC - Prakrits (vernacular or "natural" languages) develop among India's common peoples. Already flourishing in 500 BC[/b] - E , Pali and other Prakrits are chiefly known from Buddhist and Jain works composed at this time.
750 BC - Literary Sanskrit is refined over next 500 years, taking on its classical form.
700 BC - Early Smartism emerges from the syncretic Vedic brahminical (priestly caste) tradition. (It flourishes today as a liberal sect alongside Saiva, Vaishnava and Shakta sects.)
623 - 543 BC - Life of Siddhartha Gautama, the Buddha, born in Uttar Pradesh in a princely Shakya Saivite family. (Date by Sri Lankan Buddhists. Indian and other scholars favor -563 to - 483; Mahayanists of China and Japan prefer -566 to - 486 or later.)
605 BC - Nebuchadnezzar II is king of Babylon (-605 to -562). His building program makes it the world's largest and most magnificent city, slightly larger than present-day San Francisco.
600 BC - Life of Zoroaster, founder of Zoroastrianism, original religion of the Persians. His Zend Avesta, holy book of that faith, has much in common with the Rig Veda, sharing many verses. Zoroastrianism makes strong distinctions between good and evil, setting the dualistic tone of God and devil which pervades all later Western religions.
600 BC - Life of Susruta of Varanasi, the Father of surgery. His ayurvedic treatises cover pulse diagnosis, hernia, cataract, cosmetic surgery, medical ethics, 121 surgical implements, antiseptics, toxicology, psychiatry, classification of burns, midwifery, surgical anesthesia, therapeutics of garlic and use of drugs to control bleeding.
600 BC - The Ajivikas, an ascetic, atheistic sect of naked sadhus is at its height, continuing in Mysore until the 14th century. Adversaries of Buddha and Mahavira, their philosophy is deterministic, holding that everything is inevitable.
600 BC - Lifetime of Lao-tzu, founder of Taoism in China, author of Tao te Ching. Its esoteric teachings of simplicity and selflessness shape Chinese life for 2,000 years and permeate the religions of Vietnam, Japan and Korea.
599 - 527 BC - Lifetime of Mahavira Vardhamana, 24th Tirthankara, renaissance Jain master who stresses vegetarianism, asceticism and nonviolence.
560 BC - In Greece, Pythagoras teaches math, music, vegetarianism and Yoga, drawing from India's wisdom ways.
551 - 478 BC - Lifetime of Confucius, founder of Confucianism. His teachings on social ethics form the basis of Chinese education, religion and ruling-class ideology.
518 BC - Darius I of Persia (Iran) invades Indus Valley. This Zoroastrian ruler shows tolerance for local religions.
ca 500 BC - Lifetime of Kapila, founder of Sankhya Darshana, one of six classical systems of Hindu philosophy.
ca 500 BC - Dams to store water are constructed in India.
500 BC - World population reaches 100 million. India's population is 25 million, 15 million of whom live in the Ganga basin.
ca 500 BC - Over the next 300 years (according to later dating by Muller) numerous secondary Hindu scriptures (smriti) are composed: Shrauta Sutras, Grihya Sutras, Dharma Sutras, Mahabharata, Ramayana and Puranas, etc.
ca 500 BC - Tamil Sangam age (-500 to 500) begins (see -3000). Sage Agastya writes Agattiyam, first known Tamil grammar (Kulkarni places him at -8576). Tolkappiyar (Kulkarni says -2700) writes Tolkappiyam Purananuru, on grammar, stating he is recording rules on poetry, rhetoric, etc., of earlier grammarians, indicating prior high development of Tamil. Gives rules for absorbing Sanskrit words. Other similarly aged works are the poetical Paripadal, Pattuppattu, Ettuthokai Purananuru, Akananuru, Aingurunuru, Padinenkilkanakku. Some refer to worship of Vishnu, Indra, Murugan and Siva.