Bernard Lewis argues it was not as a Palestinian nation that the Arabs of Ottoman Palestine objected to Zionists, since the very concept of such a nation was unknown to the Arabs of the area at the time and did not come into being until very much later. Even the concept of Arab nationalism in the Arab provinces of the Ottoman Empire, "had not reached significant proportions before the outbreak of World War I." Tamir Sorek, a sociologist, submits that, "Although a distinct Palestinian identity can be traced back at least to the middle of the nineteenth century (Kimmerling and Migdal 1993; Khalidi 1997b), or even to the seventeenth century (Gerber 1998), it was not until after World War I that a broad range of optional "political" affiliations became relevant for the Arabs of Palestine."