After the death of Alexander the Great, his generals split his empire among themselves. One of these generals was Seleucus, received the Eastern part of the empire. He was the first member of the Seleucid Dynasty. The Seleucid Empire, and the dynasty, survived until 63 BC, when what was left of the empire became part of the Roman province of Syria.

The Seleucid empire was one of the fragments of the Macedonian empire founded by Alexander the Great. It was founded by Seleucis I Nicator, one of Alexander's rival generals. The empire stretched from western Turkey and Judea all the way to Iran, and it lasted from 312 BC to 63 BC. The Seleucid dynasty lasted about 11 generations, although the final generations were merely kings of Syria after the empire shrank to be just Syria.

Seleucid Empire was created in 312.

The Romans never conquered the Seleucid Empire.

There should be, as she played a role in the Ptolemaic dynasty. To find clues as to where to find information on her, you can google around for info and inquire at your local library for help in researching Cleopatra Thea.