On the other hand, there is the modern view, associated with scholars in the tradition of Peter Brown, in which Islam is seen to be a product of the Late Antique world, not foreign to it. This school suggests that its origin within the shared cultural horizon of the late antique world explains the character of Islam and its development. Such historians point to similarities with other late antique religions and philosophies—especially Christianity—in the prominent role and manifestations of piety in Islam, in Islamic asceticism and the role of "holy persons", in the pattern of universalist, homogeneous monotheism tied to worldly and military power, in early Islamic engagement with Greek schools of thought, in the apocalypticism of Islamic theology and in the way the Quran seems to react to contemporary religious and cultural issues shared by the late antique world at large. Further indication that Arabia (and thus the environment in which Islam first developed) was a part of the late antique world is found in the close economic and military relations between Arabia, the Byzantine Empire and the Sassanian Empire.