Most of us are taught that Buddha was born around 560 to 550 B.C. However, once we start doing some research, we find evidence that this date may be too late. Buddha may have been born much earlier.
For example, in Some Blunders of Indian Historical Research (p. 189), P. N. Oak explains that the Puranas provide a chronology of the Magadha rulers. During the time of the Mahabharata war, Somadhi (Marjari) was the ruler. He started a dynasty that included 22 kings that spread over 1006 years. They were followed by five rulers of the Pradyota dynasty that lasted over 138 years. Then for the next 360 years was the 10 rulers of the Shishunag family. Kshemajit (who ruled from 1892 to 1852 B.C.) was the fourth in the Shishunag dynasty, and was a contemporary of Lord Buddha's father, Shuddhodana. It was during this period in which Buddha was born. It was during the reign of Bimbisara, the fifth Shishunag ruler (1852-1814 B.C.), when Prince Siddhartha became the enlightened Buddha. Then it was during the reign of King Ajatashatru (1814-1787 B.C.) when Buddha left this world. Thus, he was born in 1887 B.C., renounced the world in 1858 B.C., and died in 1807 B.C. according to this analysis.
Further evidence that helps corroborate this is provided in The Age of Buddha, Milinda and King Amtiyoka and Yuga Purana, by Pandit Kota Venkatachalam. He also describes that it is from the Puranas, especially the Bhagavat Purana and the Kaliyurajavruttanta, that need to be consulted for the description of the Magadha royal dynasties to determine the date of Lord Buddha. Buddha was the 23rd in the Ikshvaku lineage, and was a contemporary of Kshemajita, Bimbisara, and Ajatashatru, as described above. Buddha was 72 years old in 1814 B.C. when the coronation of Ajatashatru took place. Thus, the date of Buddha's birth must have been near 1887 B.C., and his death in 1807 B.C. if he lived for 80 years.
Professor K. Srinivasaraghavan also relates in his book, Chronology of Ancient Bharat (Part Four, Chapter Two), that the time of Buddha should be about 1259 years after the Mahabharata war, which should make it around 1880 B.C. if the war was in 3138 B.C. Furthermore, astronomical calculations by astronomer Swami Sakhyananda indicates that the time of the Buddha was in the Kruttika period, between 2621-1661 B.C.
Therefore, the fact that Buddha lived much earlier than what modern history teaches us has a number of ramifications. First, the time of the Buddha's existence is underestimated by about 1300 years. Secondly, this means that Buddhism was in existence in the second millennium B.C. Thirdly, we also know Buddha preached against the misused Vedic rituals of animal sacrifice. Such misuse or misinterpretation of something in a culture generally only happens after a long period of prominence. So the purer aspect of Vedic culture must have been around for many hundreds if not thousands of years before its tradition began to be misused. Therefore, this pushes the Vedic period to a much earlier time from that of Buddha than originally figured, and much earlier than many people have calculated. And lastly, everything else we have figured according to the time frame of the appearance of Buddha now has to be re-calculated. Again we find that history has to be adjusted away from the speculations of modern researchers, and that many of the advancements in society and philosophy, as outlined in the Vedic texts, had taken place much earlier than many people want to admit.
(This article is found at: http://www.stephen-knapp.com - also check out "The World When Buddha Was Born")