Grammaticalization theory deals with regularities of grammatical change. The theory has been used to been used to describe and explain a wide range of linguistic phenomena. Have been some tremendous work on the development of person agreement markers, unfortunately most of the articles neglected the aspect of how personal pronouns arise. This could be owed to the reason that personal pronouns differ in their diachronic behavior presenting a challenge to grammaticalization theory. In this paper, the diachronic sources of each of the main categories of personal deixis were investigated based on a cross-linguistic perspective. The paper has also addressed the question of how, or to what extent, the development of personal pronouns is covered by grammaticalization theory.