In the Middle Ages Vainakh society felt a strong Byzantine influence that led to the adoption of Eastern Orthodox Christianity in some parts of the country (particularly the mountainous South). However, Christianity did not last long. After the devastation of the country by Tamerlane, Christianity was eroded (due to the temporary loss of contacts between Georgia and Nakh Christians) and gradually the Chechens and Ingush returned to their native, pagan beliefs (while the Bats were permanently Christianized). Islam began to spread on Nakh peoples lands from 16th and 17th centuries.