Check out this neat Disney movie chronology! Aish from Disney’s New Groove put together this timeline that shows the estimated time periods of animated Disney movies. Here’s a little bit more about it from her:
“Disney movies in order of historical setting. (Excludes most of the package films. Some films, eg The Lion King, are impossible to pin down exactly and some, like Aladdin and Treasure Planet, are anachronistic, so these are estimations. A few have been split into 2 if there is more than one time period in the movie, and sequels have been put together.)”
Source: Disney’s New Groove
Except Lion King is based on Shakespeare, so it is much older.
Lion King should be human pre-history. Tarzan is pre- WW1, but barely.