That group, also known as the Seveners, originated in a dispute over religious leadership with a group which followed Musa al-Khadim, known as the Twelvers.
The Zaydi sect of this faith dominates Yemen and dates to an early split in this religious denomination. The title Aga Khan is bestowed on the leader of another sect of this denomination, the Nizari branch of the Ismailis. That group, also known as the Seveners, originated in a dispute over religious leadership with a group which followed Musa al-Khadim, known as the Twelvers. This sect is predominant in Iran. Belief in Ali as proper successor to Muhammad characterizes, FTP, what branch of Islam contrasted with Sunni?
The Zaydi sect of this faith dominates Yemen and dates to an early split in this religious denomination.
Shia Islam or Shi'ism (prompt on "Islam" before said; do NOT accept or prompt 	                   answer of "Sunni" Islam)