Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1922 at 10 years old , he joined the Spartacus League , then the Young Communist League of Germany ( KJVD ) , the youth section of the Communist Party of Germany ( KPD ) , in 1926 and joined the KPD itself in 1929 .
Simplified: He joined the Young Communist League of Germany ( KJVD ) , the youth section of the Communist Party of Germany ( KPD ) , in 1926 and joined the KPD itself in 1929 .