From 25 B.C. to 235 A.D., five Roman provinces are established in Anatolia: Asia, Bithynia, Pontus, Galatia, and Cappadocia. During this period, numerous roads are built linking the highland cities to the Anatolian coast. Primarily designed for military use, they become important communication and trade routes. By the mid-third century, the expanding power of the Sasanian empire to the east, along with rebellious dynasts in the desert city of Palmyra to the south, threaten the collapse of the empire’s frontiers. In response, fortifications are hastily built around major cities. During the fourth and fifth centuries, urban life prospers with a revival of classical forms in literature and the arts, especially sculpture. Christianity becomes the official religion of the Roman empire in the fourth century, and churches and other ecclesiastical buildings are rapidly built.