Within the Indian subcontinent, the Bengali region developed a distinct regional style under the independent Bengal Sultanate. It incorporated influences from Persia, Byzantium and North India, which were with blended indigenous Bengali elements, such as curved roofs, corner towers and complex terracotta ornamentation. One feature in the sultanate was the relative absence of minarets. Many small and medium-sized medieval mosques, with multiple domes and artistic niche mihrabs, were constructed throughout the region. The grand mosque of Bengal was the 14th century Adina Mosque, the largest mosque in the Indian subcontinent. Built of stone demolished from temples, it featured a monumental ribbed barrel vault over the central nave, the first such giant vault used anywhere in the subcontinent. The mosque was modeled on the imperial Sasanian style of Persia. The Sultanate style flourished between the 14th and 16th centuries. A provincial style influenced by North India evolved in Mughal Bengal during the 17th and 18th centuries. The Mughals also copied the Bengali do-chala roof tradition for mausoleums in North India.