Short answers, pulled from the story.
The Madhyama Agama is an early Indian Buddhist text comprising 222 discourses in 18 chapters, preserved in the Chinese Buddhist Canon as number 26 in the Taisho Tripitaka. Its title means "Middle Collection." No copy in the original Indian language has survived.
The earliest Chinese translation of the Madhyama Agama dates to between 397 and 398 C.E. It is catalogued in the Chinese Buddhist Canon under the title Zhong Ahan Jing.
The original language of the Madhyama Agama is not definitively known. Scholar P.V. Bapat proposed that the source behind the Chinese translation was written in a form of Prakrit, an ancient Indian dialect family closer to Pali than to Sanskrit.
The Majjhima Nikaya is the Pali-language equivalent of the Madhyama Agama. The Madhyama Agama contains 222 discourses in 18 chapters, while the Majjhima Nikaya holds 152 discourses in 15 chapters. Of the Madhyama Agama's 222 discourses, 103 have a direct counterpart in the Majjhima Nikaya.
Fourteen of the 222 discourses in the Madhyama Agama have no known parallel anywhere in the Pali corpus. Scholars have traced parallels to the Majjhima Nikaya for 103 of the discourses, 87 to the Anguttara Nikaya, 17 to the Samyutta Nikaya, and 14 to the Digha Nikaya.
The first English translation of the Madhyama Agama was led by Marcus Bingenheimer as chief editor, with Bhikkhu Analayo and Rodney S. Bucknell as co-editors. Work began in 2006, and the first of three planned volumes was published in 2013.