Complex sentence: At the time of first contact with Spanish explorers, the Alachua culture area was occupied by the Potano Indians, a branch of the Timucua, who spoke the Potano dialect of the Timucua language.
Split into simpler sentences: At the time of first contact with Spanish explorers, the Alachua culture area was occupied by the Potano Indians, a branch of the Timucua. They spoke the Potano dialect of the Timucua language.