Intef III inherited a kingdom centred on Thebes during the First Intermediate Period, when authority was divided among rival royal and provincial powers. His predecessor Intef II had expanded Theban influence, while rulers based at Herakleopolis remained important opponents farther north. The new king's task belonged to that continuing contest. It is reasonable to see his reign as part of the consolidation of Theban power, but the surviving evidence does not provide a campaign-by-campaign history. Nor does it reveal a childhood spent in military camps, the condition of his treasury or the private plans he made for his successor.

One of the most useful witnesses is Tjetji, a royal official whose funerary stela is preserved in the British Museum as EA 614. Tjetji records service under both Intef II and Intef III and describes the latter's succession as that of a son following his father. The inscription preserves the king's Horus name, Nakhtnebtepnefer, and connects his reign with an administration that continued across the change of ruler. This is not simply a list of kings. It is the memorial of an official presenting his loyalty and responsibilities as the achievement of a lifetime. Like other Egyptian autobiographical inscriptions, it gives valuable evidence through the carefully shaped voice of the person being commemorated.

Intef III is generally regarded as the father of Mentuhotep II. Iah, the mother of Mentuhotep II, is consequently usually reconstructed as Intef III's wife, although the surviving family evidence is not as complete as a modern genealogy. The royal relief at Shatt er-Rigal belongs to the setting of Mentuhotep II and includes Iah, a figure named Intef and the official Khety. The identification of that Intef figure has been debated. It is therefore not a secure contemporary portrait of Intef III standing with Intef II and Tjetji. The scene is better approached as evidence for how the later court represented royal relationships and honoured service.

The royal cemetery at el-Tarif provides a different kind of testimony. The early Theban kings used saff tombs, whose name refers to a row of pillars along a courtyard facade. Their broad open spaces and rock-cut chambers created a royal burial landscape unlike the pyramid fields of the Old Kingdom. The tomb known as Saff el-Baqar is traditionally assigned to Intef III, but that attribution should not be mistaken for a surviving inscription explicitly naming him as its owner. The tomb's place within the cemetery and the sequence of the dynasty contribute to the identification. Archaeological reconstruction supplies a reasoned connection, not the same certainty as a named royal monument.

Mentuhotep II eventually defeated the rival northern kingdom and established the reunified state associated with the beginning of the Middle Kingdom. That achievement should not be projected backwards as a victory Intef III had already secured. His importance is more modest, but still real: he occupied the throne between the expansion of his predecessor and the later success of his successor. The surviving evidence gives him a place in a developing royal institution rather than the fully known personality of a heroic biography. His story is a reminder that a reign can matter even when its individual decisions have largely disappeared.