How one ought to include a region as a part of an empire is largely subjective prior to the advent of a mature concept of territoriality in international law (first copy completed only in 1908). We can only use comparative means to judge whether a region is part of the Mauryan Empire. From the way I see it, much of Northern India was under more direct control with tax collecting abilities over the locals, similar to Spanish Mexico under the Spanish Empire or Qing era Xinjiang. The Deccans is more like Spanish New Mexico or the Dusi (command general) of the Ming period in Manchuria (the northern part of both are under very little real control), Tibet, or Malacca, where you have a few small garrisons theoretically holding sway over a large swath of vassal territory not under centralized control.Then you have the Aparantha, which are autonomous tribes that seem to have recognized Mauryan suzerainty. This includes people like Tonas, Kambojas, Pitinikas, Nabhapamtis, Bhojas, Andhras and Pulindas which were "in the king's territories but not within his direct jurisdiction." Finally the Anta or Avijita are not in any way, not even nominally recognizing Mauryan suzerainty. The interior of Orissa seem to be of this type.