Intef is known for certain from only one near-contemporary monument: two inscribed blocks from the temple of Montu at Tod which were erected during Mentuhotep II's reign. The blocks represent Mentuhotep II facing the names of three of his ancestors which are identified by their proper name (nomen) and Horus name.
These are Intef (I) Sehertawy, Intef (II) Wahankh and Intef (III) Nakht-neb-tep-nefer (although in this case only the Horus names Sehertawy and Wahankh are preserved). This relief establishes the succession of kings of the 11th Dynasty.
There are no contemporary monuments which can be positively attributed to Intef I. A possible exception is a short inscription discovered in the western desert: "the assault troops of the son of Re, Intef". In the original publication of the inscription this king Intef is identified with Intef I, although Intef II has also been proposed as a possibility. The inscription is located in the vicinity of an inscription commissioned by the contemporary Coptite nomarch named Tjauti (see below).
Intef I is most likely attested on later king lists, but this remains uncertain as his name is either lost or damaged. In the Karnak king list a king Intef appears next to "Men...", most likely Mentuhotep I, as part of the latter's Horus name, "the ancestor", is still visible. The few remains of Intef I's Horus name fit to Sehertawy. The name and duration of the reign of Intef I are not preserved in the Turin Canon, although from an analysis of the available space, it is possible that Intef I was mentioned in what is now a lacuna affecting entry 5.13. The durations of the reigns of the other 11th Dynasty kings are preserved in the Turin Canon and add up to 127 years. Furthermore, the summary of reigns of this Dynasty is also preserved in the Turin Canon and is given as 143 years. On the strength of these much later fragments, the two lost reigns of Mentuhotep I and Intef I have been calculated to add up to 16 years, further implying that Intef's reign lasted for less than 16 years. Thus the duration of Intef's reign is often reported to be between 4 and 16 years. Intef I was succeeded by his brother Intef II who pursued the war with the northern neighbors of the Theban kingdom.