Balāš VI succeeded his father Balāš V in 207/8. Not many years passed before his authority was challenged by his brother Artabanus IV (still often mentioned as Artabanus V; the new numbering is used here for the reasons given in artabanus). Fighting between the two probably began ca. 213. Artabanus appears to have succeeded in taking over large parts of the empire. The fact that many of his coins are probably from Ecbatana indicates that he controlled Media, and the inscription on a stele found at Susa shows that he held that city. On the other hand coin-finds show that Seleucia remained in Balāš VI’s possession (McDowell, p. 200).

No doubt the internecine strife among the Parthians encouraged the Romans to embark on an “active” course. In 213/4 Caracalla invited the king of Osrhoene, Abgar IX, to Rome and then flung him into jail, and later he attempted to play the same trick on the king of Armenia (name unknown). In revulsion against the imprisonment of the king of Osrhoene, an anti-Roman rebellion broke out (for details, see Chaumont, pp. 134ff.; Maricq, pp. 297ff.).

By this time the emperor Caracalla was probably already planning to start a new Parthian war. In search of a pretext, he sent a demand to Balāš VI for the delivery of two fugitives, a philosopher named Antiochus and a certain Tiridates (whether the latter was an Armenian prince or a brother of Balāš V who had gone over to Septimius Severus in his second Parthian campaign is uncertain; see Chaumont, p. 155). Surprisingly, Balāš VI delivered the two hostages, thus depriving Caracalla of his pretext. Instead Caracalla began with an expedition against Armenia. He gave the command to a former slave and theater-dancer named Theocritus. The venture was a fiasco.

Before long, Caracalla concocted another pretext for war against the Parthians. In 216 he sent a request to Artabanus IV for the hand of his daughter in marriage, and Artabanus refused. Opinions differ on the question whether this proposal was genuine (Ziegler, p. 133) or not meant seriously (Schur, col. 2028). Caracalla then set out on “his” war in the summer of 216. The fact that the Roman emperor addressed the request for a bride to Artabanus IV is generally seen as evidence that Artabanus IV had finally won the contest with his brother Balāš VI (Debevoise, p. 265; Chaumont, p. 155); but, against this, coins of Balāš VI are known to have been minted at Seleucia until at least 221/2 (Le Rider, p. 461; Sellwood, p. 290; until 222/3 according to McDowell, pp. 200, 237). It is even possible that a silver tetra-drachm from the year 228 should be attributed to Balāš VI (opinion of Sellwood, p. 290). If so, there would be reason to suppose that, after the last decisive battle in 224 or thereabouts when the Sasanian beat the Parthians and killed Artabanus IV, Balāš VI kept the resistance against them going for some time, mainly in Mesopotamia.