Simplify the following text for a Grade 9 native English-speaking person.
Original: He is well-known for his nationalist policies and version of pan-Arabism , also referred to as Nasserism , which won a great following in the Arab World during the 1950s and 1960s .
Simplified: Nasser 's version of pan-Arabism , which is often called `` Nasserism '' , was very popular in the Arab world during the 1950s and 1960s .