"Pharaonism" rose to political prominence in the 1920s and 1930s during the British occupation, as Egypt developed separately from the Arab world. A segment of the most Westernized upper class argued that Egypt was part of a Mediterranean civilization. This ideology largely developed out of the country's lengthy pre-Islamic pre-Arab history, the relative isolation of the Nile Valley and the mostly homogeneous indigenous non-Arab genetic ancestry/ethnicity of the inhabitants,[32] regardless of current religious identity.