As early as the 240s , Odaenathus inflated the Palmyrene army , recruiting the desert nomads and increasing the numbers of the Palmyrene heavy cavalry units ( clibanarii ) . In 252 , Persian emperor Shapur I started a full @-@ scale invasion of the Roman provinces in the east . During the second campaign of the invasion , Shapur conquered Antioch and headed south where his advance was checked in 253 by Emesa 's priest king Uranius Antoninus . The events of 253 was mentioned in the works of the sixth century historian John Malalas who also mentioned a leader by the name " Enathus " inflicting a defeat upon the retreating Shapur near the Euphrates . " Enathus " is probably identical with Odaenathus , and while Malalas ' account indicate that Odaenathus defeated the Persians in 253 , there is no proof that the Palmyrene leader engaged Shapur before 260 and Malalas ' account seem to be confusing Odaenathus ' future actions during 260 with the events of 253 .