I have traditionally heard that it is forward bends followed by backbends. Makes sense.
But recently I have been researching Indra Devi’s yoga (see her website). Her practice states-- Sun salutes, followed by backbends, then forward bends, inverted, twist, standing, lotus. Kinda surprising to me.
I figure Indra Devi must know what she was talking about. After all, she was one of the great students of Krishnamaycha— along with Desichikar, Iyengar, Jois, et al. It is a great tradition. Hard to argue with.