That cannot be the case.
5 years per turn * 407 turns = 2035 years since the game started.
3000 BC - 2035 yrs = 965 BC
Given that the Romans and the Tamils spawn after that date, your answer is clearly false. I suspect that when the game starts, each turn is more than 5 years.
Fortunately, you do have a chart of dynasties, complete with dates. According to it, as "35 years of peace" passed since Samrat Satakarni,'s reign, so we are now in the year 100 BC (assuming that my stories took place shortly after Satakarni's death, in 135 BC). It makes sense when one examines it from the Greco-Roman perspective as well, as the conquest of Greece IRL happened in 146 BC. (It better be, as I'm pretty sure that war was scripted.)