Simplify the following text for a Grade 10 native English-speaking person.
Original: While in Chile ( 1556 â `` 63 ) he fought against the Araucanians , and there he began the epic poem La Araucana , considered the greatest Spanish historical poem .
Simplified: While in Chile ( 1556 â `` 63 ) he fought against the Araucanian , and there he began the epic poem La Araucana , said to be the greatest Spanish historical poem .