The ancient and Late Antique history of Eurasia could be reasonably (if not generously) characterised as a series of experiments in assembling communities through two sometimes complementary, contradictory or overlapping processes. The first was unambiguously political: building states and empires through conquest and some combination of occupation, emigration, colonisation, administration and exploitation. The other was ambiguously ideological, intellectual, spiritual and cultural: creating religious and philosophical systems of thought and conduct through some combination of inspiration, revelation, reflection and systematic teaching. Some 1,500 years or so after the end of Late Antiquity some of the religious and philosophical systems have proven more durable than the necessarily fragile political ones, in large measure because they have ridden the back of those strong polities: from Hellenism through Christianity to Confucianism, the biggest success stories feature ruling elites that offered robust sanction and patronage. What would Near Eastern history be like had the Sasanian shah Wahrām I followed his predecessors in favouring, rather than imprisoning, Mani (d. 276)? The opposite scenario poses questions too. How would Chinese history appear had the Song failed to oversee the rise of Neo-Confucianism?