Complex sentence: Zaydis were the oldest branch of the Shia and the largest group amongst the Shia before the Safavid Dynasty in the sixteenth century and currently the second largest group, Zaidi's do not believe in the infallibility of Imāms, but promotes their leadership and divine inspiration.
Split into simpler sentences: Zaydis were the oldest branch of the Shia and the largest group amongst the Shia before the Safavid Dynasty in the sixteenth century and currently the second largest group. Zaidis do not believe in the infallibility of Imāms, but promote their leadership and divine inspiration.