Around the start of the Common Era, the family trees of the gens Julia and the gens Claudia became intertwined into the Julio-Claudian family tree as a result of marriages and adoptions. Descendancy of the emperors of the Julio-Claudian dynasty The Julio-Claudian dynasty was the first dynasty of Roman emperors. All emperors of that dynasty descended from Julii Caesares and/or from Claudii. Marriages between descendants of Sextus Julius Caesar and Claudii had occurred from the late stages of the Roman Republic, but the intertwined Julio-Claudian family tree resulted mostly from adoptions and marriages in Imperial Rome's first decades. Note that descendancy of the Julii Caesares before the generation of Julius Caesar's grandfather is in part conjectural, but as presented by scholars. |- |style="text-align: left;"| Simplified By generation In the Julio-Claudian dynasty of Roman emperors, the lineage of the Julii Caesares was separated from those of the Claudii up to Augustus' generation. The next generation had both Claudii with a Julia as ancestor, as Claudii adopted into the Julii Caesares family. After Tiberius, the remaining three emperors of the dynasty had, outside adoptions, ancestors in both the Julian and the Claudian families. Generation of Julius Caesar's grandfather Gaius Julius Caesar II and Lucius Julius Caesar II may have had Sextus Julius Caesar, the military tribune of 181 BC, as a common ancestor. Generation of Julius Caesar's father This generation of Julii Caesares has two consuls: Sextus Julius Caesar in 91 BC, and Lucius Julius Caesar the next year. This generation has also two female descendants very close to the centers of power by their marriages: Julia, the daughter of Gaius Julius Caesar II was married to seven-times consul Gaius Marius, while Julia, the daughter of Lucius Julius Caesar II was married to the two-times consul and Roman dictator Lucius Cornelius Sulla, who had successfully challenged Marius' power. For ensuing generations, Gaius Julius Caesar (proconsul of Asia), married to a consul's daughter, and Lucius Julius Caesar proved to be quintessential ancestors of those who held Imperial power in the Julio-Claudian dynasty. Julius Caesar's generation Following Sulla's example Julius Caesar's and Pompey's first marriages were with women of their own generation, later marrying women of a younger generation. After being betrothed to Cossutia, Julius Caesar's first wife was Cornelia, the mother of Julia. The younger of Caesar's two sisters married Marcus Atius Balbus: they were ancestors of all the Julio-Claudian emperors, apart from