About a year and a half ago, give or take a few weeks.
It's a long story. But Ares corrupted man. My mother led a rebellion to free the Amazons while Zeus led the other gods against Ares. With his dying breath Zeus gave my people Themyscira so we would stay safe from Ares and live in peace. I only left Themyscira in an attempt to stop Ares from leading mankind to their destruction.