The papacy became involved and encouraged volunteers from the rest of Europe to join the Christian forces in Spain in a crusade against the Muslims. The impetus for the Crusades came from a major defeat for the Byzantines in Asia Minor at the hands of a new invading group from Central Asia, the Seljuk Turks. An Asian tribe that adopted Islam and moved into the Islamic Empire proper, they began their reign by a process of expansion similar to the earlier stages of Islamic kingdoms, capturing most of Asia Minor. Changes brought on by wars, plagues, and religious controversy affected the structure and dynamics of families, the organization of work, and the culture in many parts of Europe. Despite farming improvements, it became increasingly difficult for the towns and countryside to feed and support the growing population, and millions died around Europe during the Great Famine of 1315–1322.