In ‘A History of India’, (K. Antonova, G. Bongard-Levin, G. Kotovsky; Progress Publishers, Moscow, 1973) the chronology of Asoka is discussed as below:
“The dates of Ashoka’s reign are still subject of great controversy among historians, although his inscriptions contain important information bearing on this question. In the so-called Major Rock Edicts made twelve years after Ashoka’s coronation simultaneous mention is made of five Hellenistic rulers, which means that in the year the edict was made all five kings were still alive. This could have meant 256 or 255 B.C. This would imply that Ashoka’s reign began in approximately 268 B.C.”
“Interesting research has been carried out with regard to astronomical data contained in the legends of Ashoka. In Buddhists legends we read of an eclipse of the Sun – an even which seems to have coincided in time with the journey Ashoka undertook to visit certain
Buddhist shrines. Scholars have ascertained that in 249 B.C., during Ashoka’s reign, a solar eclipse actually took place. In one of the king’s edict’s issued during the twentieth year of his reign there is reference to his visit to
Buddha’s birth place. All this when taken together gives us reason to assume that Ashoka’s reign began in 268 B.C. Certain other source materials confirm this date: if Bindusara reigned for 25 years, as is stated in the puranas, which contain dynastic lists then the year 268 B.C is the year of Ashoka’s accession. Buddhist tradition has mention of the fact that the coronation of Ashoka took place 218 years after Buddha’s death, which as many scholars agree might have taken place in the year 486 B.C. If one follows this tradition, we shall have the very same date for the beginning of Ashoka’s reign – 268 B.C.”