Mstislav of Chernigov. Some chronicles, however, report that Rogneda was Mstislav's mother. Bulgarian wife Another wife was a Bulgarian lady, whose name is given by Tatishchev as Adela. Historians have disagreed as to whether she came from Volga Bulgaria or from Bulgaria on the Danube. According to the Primary Chronicle, both Boris and Gleb were her children. This tradition, however, is viewed by most scholars as a product of later hagiographical tendency to merge the identity of both saints. Their names point to different origins, indicating that Adela was not fully Bulgarian. Anna Porphyrogenita Anna (March 13, 963 - 1011/12) was the daughter of Byzantine Emperor Romanos II () and the Empress Theophano. She was also the sister of Emperors Basil II Bulgaroktonos (the Bulgar-Slayer; ) and Constantine VIII. Anna was a Porphyrogenita, a legitimate daughter born in the special purple chamber of the Byzantine Emperor's Palace. Anna's hand was considered by Vladimir such a prize that he allegedly became Christian (988) just to marry her. German wife Thietmar of Merseburg, writing from contemporary accounts, mentions that Bolesław I of Poland captured Vladimir's widow during his raid on Kiev in 1018 but Anna is known to have predeceased Vladimir by four years. So historians long had no clue who this wife was. The emigré historian Nicholas Baumgarten, however, pointed out that in the controversial records called the Genealogia Welforum and the Historia Welforum Weingartensis one daughter of Count Kuno von Oenningen (future Duke Konrad of Swabia) by "filia Ottonis Magni imperatoris" (Otto the Great's daughter; possibly Rechlinda Otona [Regelindis], claimed by some as a legitimate daughter born from his first marriage with Edith of Wessex and by others as an illegitimate child) married "rex Rugorum" (king of Russia). He interpreted this evidence as pertaining to Vladimir's last wife. It is believed that the only child of this alliance was Dobronega, or Maria, who married Casimir I of Poland between 1038 and 1042. As her father Vladimir died about 25 years before that marriage and she was still young enough to bear at least five children, including two future Polish dukes (Bolesław II of Poland, who later became a king, and Wladyslaw Herman), it is thought probable that she was Vladimir's daughter by the last marriage. Yaroslav's parentage There is also a case for Yaroslav's descent from Anna. According to this theory, Nestor the Chronicler deliberately represented Yaroslav as Rogneda's son,