The 1989 film is approximately 5 hours long, and it is based on a theatrical production that was even longer which Brook had staged in 1985 and which toured the world for four years. The cast is very international, with actors and actresses not just from India but from all Africa, Asia, and Europe. You can see a list of the cast in this Wikipedia article; one of the actors you might recognize is Ciarán Hinds as Ashwatthaman — he plays Mance Rayder in Game of Thrones. I first saw the film when it was broadcast on PBS in 1989, and it was my first introduction to the world of Indian epics; I've spent the last 25 years learning more!
Peter Brook, born in 1925, is best known for his work with the Royal Shakespeare Company in England. You can read more about his life and career at Wikipedia. Here is a photograph of Brook with the Mahabharata troupe:
Brook is now 92 years old and, inspired by the Syrian civil war, he has created a new play inspired by the Mahabharata: Battlefield. It is the story of Yudhishthira, victor and survivor of the war. What will he do now? You can listen to this NPR broadcast to learn more; here is the transcript:
A photograph of the production: