The capital of Harshavardhana's Empire was Kannuaj. He ruled from 606 AD to 647 AD. His Empire extended from Punjab to northern Orissa and from Himalayas to the bank of Narmada River. Harshavardhana belonged to the Pushyabhuti dynasty, founded by Naravardhana close of the 5th or beginning of the 6th century A.D. It was only under the king of Thaneswar Prabhakarvardhana (father of Harshavardhana), the Pushyabhuti dynasty flourished and he assumed the title of Maharajadiraj. Harshavardhana succeeded the throne in 606 A.D.
The six schools of philosophy developed in India with the beginning of the Christian era. These were as following: 1) Yoga, 2) Nyaya, 3) Mimamsa, 4) Vedanta, 5) Vaisheshikha and 6) Samkhya. The exact dates of formalizing the six systems are not known, as the studies were originally purely oral, since writing had not yet been created. However, estimates generally range from about 2,000-3,000 or more years ago. Some say the roots of these are as much as 5,000-10,000 years ago, or more.