In Old Babylonian Sumerian literature, the temporal phrases u₄-ba and u₄-bi-a typically occur in complementary distribution. Previous analyses have focused on morphological disparity to differentiate the two. The present paper considers pragmatic functions within a larger discourse structure, analyzing them as discourse markers, specifically temporal connectives. In this study based on a corpus analysis of Old Babylonian literary compositions, I argue that in Sumerian discourse, u₄-ba primarily marks perspectival shifts and refocusing, and u₄-bi-a indexes sequential and consequential action.