Collectivization is the process of change towards a collectivist system. Collectivism is defined as "the system of ownership and control of the means of production and distribution by the people collectively, usually under the supervision of a government" (American Heritage Dictionary). In other words, collectivasation is what we call الاشتراكية or التحول الاشتراكي

As written, however, the sentence clearly points to something else, to political structure, not economic structure. The writer is alluding to the state-building (later, empire-building) enterprise that followed the consolidation of Islam in Arabia, whereas previously there had been only a tribal structure. In this sense, the Arabic word would be التوحيد, or if two words are OK, التوحيد السياسي or التوحيد الاجتماعي

The writer could have used a more accurate expression, like "a facilitation for unification." We do not know the reasons for the semantical misuse (or abuse), because we do not know the rest of the text. Some writers simply become fascinated by certain words and feel impelled to use them. On the other hand, the writer may be trying to hint to what he/she sees as a collectivist tendency in Islam.