It is evident from what has been said, that before 500 A.D. literary chronology, even in the Sanskrit period, is almost entirely relative, priority or posteriority being determined by such criteria as development of style or thought, the mention of earlier authors by name, stray political references as to the Greeks or to some well-known dynasty, and allusions to astronomical facts which cannot have been known before a certain epoch.
Source: tatoeba (10883575)