There are a few external mentions of him, primarily documents of the Kingdom of Hungary, a contemporary Italian chronicle, a late pisanie, an inscription on the walls of Curtea de Argeș Cathedral and an important quantity of coins (ducati, dinari and bani) which were emitted by the voievod.

These tense relations which preceded the fight are confirmed by the registers of the Venetian Republic where, in the same year, a large order of full-equip armors made by the Wallachian voievod appears.

On the contrary, in an order given to the landlord of Orsova in 1382 through which he was obliged to forbid any foreign trader to enter Wallachia with merchandise and to keep guard of the border "day and night" reporting everything that happened, there is no mention of a Hungarian ban of Severin and Orsova appears as border point thus suggesting that the Eastern part of Banat was annexed by the Wallachian voievod Radu I.

It is true that the relations between the Wallachian rulers Vladislav I and Radu I and the Bulgarian Tsars from Tarnovo and Vidin, Shishman and Ivan Sratsimir were very tensed, the latter being themselves in conflicts for the succession of the paternal throne.

Archaeological digs carried out in 1920 around the voievodal necropolis (in the grounds of the Curtea de Arges Cathedral), have revealed a rich tomb dating from the end of the 14th century, presumed to be that of Radu I.

His attire, jewelry and other accessories show him as a powerful feudal ruler, with all the pomp of the Wallachian court supported by evidence that is Radu I lost tomb.