Very little is known of Bessas' early life and career: he joined the imperial army in his youth and according to Procopius was already "experienced in war" by 503, when the Anastasian War with the Sassanid Persians broke out.
Bessas reappears in 531, during the Iberian War against Persia, when he was appointed dux Mesopotamiae, with Martyropolis as his base.