Complex sentence: The history of the current WJST can be traced back to the late 1960s, when the station, as WBZY, made its debut as a competitor to well-established crosstown competitor WKST, which had already been on the air for thirty years at the time.
Split into simpler sentences: The history of the current WJST can be traced back to the late 1960s. WBZY began as a head-on competitor to WKST, which had already been on the air for thirty years at the time.