Andrei Kobyla was documented in contemporary Russian chronicles only once, in 1347,^[1][2] when he was sent by Simeon of Moscow to Tver with the purpose of meeting Simeon's bride, who was a daughter of Aleksandr Mikhailovich of Tver. Neither his pedigree nor exact position at court are known, hence speculation abounds.^[3]

Later generations assigned to Kobyla the most illustrious pedigrees. They first claimed that he had arrived in Moscow in 1341 from Prussia,^[3] where his father, Glanda Kambila, was a famous Prussian holdout against the conquest of Balts by the Teutonic knights. Teutonic Order records do speak of a rebel named Glande.^{[citation needed]}

In the late 17th century, after the Romanov's elevation to Russia's ruling dynasty, this origin story was replaced by a more grandiose lineage. A fictional line giving Andrei Kobyla's descent from Julius Caesar was published. 16th-century genealogies mention five of Andrei's sons: Simeon Zherebets, Alexander Yolka, Vasily Vantey, Gavrila Gavsha, and Fyodor Koshka.^{[citation needed]}