Antiochus I was half Sogdian, his mother Apama, daughter of Spitamenes, being one of the eastern princesses whom Alexander the Great had given as wives to his generals in 324 BC.
The Seleucids fictitiously claimed that Apama was the alleged daughter of Darius III, in order to legitimise themselves as the inheritors of both the Achaemenids and Alexander, and therefore the rightful lords of western and central Asia.

In 294 BC, prior to the death of his father Seleucus I, Antiochus married his stepmother, Stratonice, daughter of Demetrius Poliorcetes.
The ancient sources report that his elderly father reportedly instigated the marriage after discovering that his son was in danger of dying of lovesickness.
Stratonice bore five children to Antiochus: Seleucus (later executed for rebellion), Laodice, Apama II, Stratonice of Macedon and Antiochus II Theos, who succeeded his father as king.

The Ruin of Esagila Chronicle, dated between 302 and 281 BC, mentions that a crown prince, most likely Antiochus, decided to rebuild the ruined Babylonian temple Esagila, and made a sacrifice in preparation.
However, while there, he stumbled on the rubble and fell.
He then ordered his troops to destroy the last of the remains.

On the assassination of his father in 281 BC, the task of holding together the empire was a formidable one.
A revolt in Syria broke out almost immediately.
Antiochus was soon compelled to make peace with his father's murderer, Ptolemy Keraunos, apparently abandoning Macedonia and Thrace.
In Anatolia he was unable to reduce Bithynia or the Persian dynasties that ruled in Cappadocia.

In 278 BC the Gauls broke into Anatolia, and a victory that Antiochus won over these Gauls by using Indian war elephants (275 BC) is said to have been the origin of his title of Soter (Greek for "saviour").

At the end of 275 BC the question of Coele-Syria, which had been open between the houses of Seleucus and Ptolemy since the partition of 301 BC, led to hostilities (the First Syrian War).
It had been continuously in Ptolemaic occupation, but the house of Seleucus maintained its claim.
War did not materially change the outlines of the two kingdoms, though frontier cities like Damascus and the coast districts of Asia Minor might change hands.

In 268 BC Antiochus I laid the foundation for the Ezida Temple in Borsippa.
His eldest son Seleucus had ruled in the east as viceroy from c. 275 BC until 268/267 BC; Antiochus put his son to death in the latter year on the charge of rebellion.
Around 262 BC Antiochus tried to break the growing power of Pergamum by force of arms, but suffered defeat near Sardis and died soon afterwards.
He was succeeded in 261 BC by his second son Antiochus II Theos.
Antiochus I was half Sogdian, his mother Apama, daughter of Spitamenes, being one of the eastern princesses whom Alexander the Great had given as wives to his generals in 324 BC. The Seleucids fictitiously claimed that Apama was the alleged daughter of Darius III, in order to legitimise themselves as the inheritors of both the Achaemenids and Alexander, and therefore the rightful lords of western and central Asia.
In 294 BC, prior to the death of his father Seleucus I, Antiochus married his stepmother, Stratonice, daughter of Demetrius Poliorcetes. The ancient sources report that his elderly father reportedly instigated the marriage after discovering that his son was in danger of dying of lovesickness. Stratonice bore five children to Antiochus: Seleucus (later executed for rebellion), Laodice, Apama II, Stratonice of Macedon and Antiochus II Theos, who succeeded his father as king.
The Ruin of Esagila Chronicle, dated between 302 and 281 BC, mentions that a crown prince, most likely Antiochus, decided to rebuild the ruined Babylonian temple Esagila, and made a sacrifice in preparation. However, while there, he stumbled on the rubble and fell. He then ordered his troops to destroy the last of the remains.
On the assassination of his father in 281 BC, the task of holding together the empire was a formidable one. A revolt in Syria broke out almost immediately. Antiochus was soon compelled to make peace with his father's murderer, Ptolemy Keraunos, apparently abandoning Macedonia and Thrace. In Anatolia he was unable to reduce Bithynia or the Persian dynasties that ruled in Cappadocia.
In 278 BC the Gauls broke into Anatolia, and a victory that Antiochus won over these Gauls by using Indian war elephants (275 BC) is said to have been the origin of his title of Soter (Greek for "saviour").
At the end of 275 BC the question of Coele-Syria, which had been open between the houses of Seleucus and Ptolemy since the partition of 301 BC, led to hostilities (the First Syrian War). It had been continuously in Ptolemaic occupation, but the house of Seleucus maintained its claim. War did not materially change the outlines of the two kingdoms, though frontier cities like Damascus and the coast districts of Asia Minor might change hands.
In 268 BC Antiochus I laid the foundation for the Ezida Temple in Borsippa. His eldest son Seleucus had ruled in the east as viceroy from c. 275 BC until 268/267 BC; Antiochus put his son to death in the latter year on the charge of rebellion. Around 262 BC Antiochus tried to break the growing power of Pergamum by force of arms, but suffered defeat near Sardis and died soon afterwards. He was succeeded in 261 BC by his second son Antiochus II Theos.
Antiochus I Soter