Short answers, pulled from the story.
The Mahīśāsaka sect emerged from the dispute in the Second Buddhist Council, a moment of division that reshaped early Buddhism. Historical records offer conflicting accounts about which group came first.
The sect is thought to have first originated in the Avanti region of India. From its roots in Avanti, the Mahīśāsaka sect spread across ancient Asia with remarkable reach.
In both sources, members of the Mahīśāsaka sect are described as wearing blue robes. The relevant portion of the Mahāsāñghika Śāriputrapariprçchā reads: The Mahīśāsaka school practice dhyāna, and penetrate deeply. They wear blue robes.
Their founder was a monk named Purāna, who is venerated at length in the Mahīśāsaka Vinaya. This text remains preserved in the Chinese Buddhist canon today.
The Mahīśāsaka sect believed that it was not possible for women to become buddhas. David Kalupahana writes that the Mahīśāsakas believed women essentially could not change the nature of their minds or physical bodies.