how did the discoveries of the greeks change from the time of pythagoras to the time of eratosthenes? ASAP

In ancient Greek they were primarily using tetra-chords and there was three main standard divisions of these tetra-chords called genus.

In the same era Pythagoras discovers the relationship between intervals and ratios, 3:2 for a perfect fifth is an example. I've also read that the ancient Greeks used Pythagoras findings to help tune the tetra-chords since they spann a perfect fourth. However it got me wondering:

A) Did the ancient Greeks use Pythagoras findings to create the tetra-chord in the first place or did they just use it for tuning later on?

B) If Pythagoras did not have anything to do with the creation of tetra-chords, then who did?

Explanation:

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