When Buddhist missionaries arrived, they naturally gravitated to caves for use as temples and abodes, in accord with their religious ideas of asceticism and the monastic life. The Western Ghats topography, with its flat-topped basalt hills, deep ravines, and sharp cliffs, was suited to their cultural inclinations. The earliest of the Kanheri Caves were excavated in the 1st and 2nd centuries B.C., as were those at Ajanta, which were occupied continuously by Buddhist monks from 200 BCE to 650 AD. As the Buddhist ideology encouraged involvement in trade, monasteries often became stopovers for inland traders and provided lodging houses along trade routes. As mercantile and royal endowments grew, cave interiors became more elaborate, with interior walls decorated in paintings, reliefs, and intricate carvings. Numerous donors provided the funds for the building of these caves and left donatory inscriptions, including laity, members of the clergy, government officials, and even foreigners such as "Yavanas" (Greeks) representing about 8% of all inscriptions. Facades were added to the exteriors while the interiors became designated for specific uses, such as monasteries (viharas) and worship halls (chaityas). Over the centuries, simple caves began to resemble free-standing buildings, needing to be formally designed and requiring highly skilled artisans and craftsmen to complete. These artisans had not forgotten their timber roots and imitated the nuances of a wooden structure and the wood grain in working with stone.