The table below collects some comparisons of ancient measurements of periods on the sky. The "synodic" period is the time required for a planet (or the moon) to come back to the same apparent place on the sky relative to the sun. 

The table also emphasizes the importance of Venus to the Maya and of Mars to the Babylonians.

Because these ancient astronomers did not use accurate means of time keeping, their observations would have been uncertain in time by something like an hour, with the additional uncertainties in locating the planet accurately against the backdrop of fixed stars. It is easy to calculate, then, that such accuracies required a coordinated effort over a century or two. That is, the differences in the values they determined and the modern (correct) ones are approximately equivalent to an error of an hour or two over a century.

Obviously, the efforts in astronomy required for such accurate determinations required a parallel strong effort in mathematics. The Babylonians developed a number system with base 60 and the Maya with base 20. For comparison, our system has base 10. Thus, to the Maya, 20 was written as 10 (one times twenty plus zero times one) whereas for us it is written 20 (two times ten plus zero times one). The base 60 system of the Babylonians, combined with their use of astronomy for timekeeping, is the underlying reason we have 60 seconds in a minute and 60 minutes in an hour.