This is what I can recollect from memory at present:
Late July 2011: Genesis is established. Genesis occupies Konohagakure, and is temporarily allied with the Leaf.
Late October 2011: Shiizuki surrenders the position of Hokage to Yuumei before disappearing. Genesis is incorporated into Konohagakure, and the local Kage count is rollbacked (from Rokudaime) to Godaime.