The Seleucidae had severe struggles with the Ptolemies for the possession of the southern part of Syria.
Till the 15th century the Jews usually followed the era of the Seleucidae or of Contracts.
The era of the Seleucidae dates from the time of the occupation of Babylon by Seleucus Nicator, 311 years before Christ, in the year of Rome 44 2, and twelve years after the death of Alexander the Great.
It was adopted not only in the monarchy of the Seleucidae but in general in all the Greek countries bordering on the Levant, was followed by the Jews till the 15th century, and is said to be used by some Arabians even at the present day.
According to the computation most generally followed, the year 312 of the era of the Seleucidae began on the ist of September in the Julian year preceding the first of our era.