Saracoglu presents some round numbers of centuries, nothing more. From that, we can begin to construct a chronological framework.
Period zero (3+ years): During the Grand Survey, the Olga under Captain Gray discovers and explores many extrasolar planets, including Ythri and Avalon. Reckoning from that arbitrary zero:
150 A human group led by an old trade pioneer settles Avalon under Ythrian protection. Some Ythrians move to Avalon.
200 The Polesotechnic League collapses.
500 Terran-Ythrian War.
700 The McCormac Rebellion and its aftermath.
722 The Dennitzan crisis.
This doesn't fit with the existing Chronology, does it?