The things I'm sure about - it's tough to see everything with the picture size, but this is a depiction of the Buddha's moment of enlightenment. The fingers pointed down and the palm up are the "world witnessing" mudra - the Buddha's response to Mara the tempter when asked who would bear witness to his spiritual accomplishments. The naked women on the lower right are Mara's three daughters - craving, passion, and antagonism (Tanha, Raga, Arati) who came to tempt the Buddha. All the wacky looking beasts raging around the Buddha is Mara's army.
Less sure about - the "Buddha" up top is probably Maitreya - the Buddha who will supposedly follow the Shakyamuni. I'm thinking maybe the folks in the two upper corners are depictions of the six paramitas (giving, concentration, energy, virtue, patience, wisdom)? No idea about the stuff at the bottom. Maybe that's Dipankara (the Buddha before the current one) in the middle with the attendants?
PS - This should be a comment, but I don't have enough text space!