The birth of OKRs can be traced back to Peter Drucker, one of the first managerial thinkers, who, in the 1950s introduced a system called “Management by Objectives” (MBOs) that called for setting objectives for everyone who works in a company.
These goals had to “lay out what contributions a given individual and their unit are expected to make to help other units obtain their objectives.”
So, you could say OKRs are a more advanced version of MBOs.