King Mohammed Zahir Shah ascended to the throne and reigned from 1933 to 1973. Zahir's cousin, Mohammad Daoud Khan, served as Prime Minister from 1954 to 1963. The Marxist People's Democratic Party of Afghanistan (PDPA)'s strength grew considerably in these years. In 1967, the PDPA split into two rival factions, the Khalq (Masses) faction headed by Nur Muhammad Taraki and Hafizullah Amin and the Parcham (Flag) faction led by Babrak Karmal. The leaders of the Khalq faction tended to be Pashtuns from a poorer background while the leaders of the Parcham faction were usually Farsi-speakers from the Tajik and Hazara ethnic groups who came from well-off backgrounds. Symbolic of the different backgrounds of the two factions were the fact that Taraki's father was a poor Pashtun herdsman while Karmal's father was a Tajik general in the Royal Afghan Army. More importantly, the radical Khalq faction believed in rapidly transforming Afghanistan by violence if necessary from a feudal nation into a Communist nation while the moderate Parcham faction favored a more gradualist and gentler approach, arguing that Afghanistan was simply not ready for Communism and would not be for some time. The Parcham faction favored building up the PDPA as a mass party in support of the Daoud Khan government while the Khalq faction were organized in the Leninist style as a small, tightly organized elite group, allowing the latter to enjoy ascendancy over the former.