The mandate system created an identity crisis among Arab nationalists that led to the growth of competing nationalisms: Arab versus Islamic versus the more parochial nationalisms of the newly created states.
The guiding principle of the mandate system was that the states concerned should remain under the tutelage of the mandatory power until such time as they were able to "stand alone," a period that, although not specified, was still understood to be finite.
Under the mandate system, Syria and Lebanon went to the French. The British took over Palestine and three Ottoman provinces of Mesopotamia and created modern-day Iraq.
The mandate period was relatively short-lived, ending with the creation of Israel from the former Palestine mandate in 1948.
For further reading, see links below:
science.jrank.org
www.npr.org
motherearthtravel.com