Zerah or Zérach (זֶרַח / זָרַח "sunrise" Standard Hebrew Zéraḥ / Záraḥ, Tiberian Hebrew Zéraḥ / Zāraḥ) refers to several different people in the Hebrew Bible.
Zerah was the name of an Edomite Chief. He was listed as the second son of Reuel, son of Basemath, who was Ishmael's daughter and one of the wives of Esau the brother of Jacob (Israel) (Genesis 36:13 and 36:17).
According to the Book of Genesis, Zerah was the son of Tamar and of Judah, and was the twin of Pharez. This same Zerah is briefly mentioned in the New Testament in Matthew 1:3.
Zerah is also listed as the ancestor of Achan, who was stoned to death as recounted in the Book of Joshua (Joshua 7:18 and 7:24, where Achan is called the son of Zerah, skipping the father and grandfather).
The Bible also identifies Zerah as the name of the founder of one of the Simeonite clans.
Zerah the Cushite is mentioned by the Book of Chronicles as having invaded the Kingdom of Judah with an enormous army, in the days of Asa. According to the text, when Zerah's army reached that of Asa at Zephathah, Zerah's army was utterly defeated, by divine intervention, and Asa's forces collected a large volume of spoils of war.
The invasion, and its implied time-frame, means that the traditional view was to consider this Zerah to have actually been Osorkon II or Osorkon I, both being rulers of Egypt. Osorkon II is known to have entered the Kingdom of Judah with a huge army in 853 BC; however, rather than attacking Judah, the army was just passing through, on its way to attack the Assyrian forces. In addition, Asa's reign is traditionally dated to have ended in 873 BC. In the Book of Kings, which doesn't mention Asa's defeat of Zerah, Asa is described as being extremely weak from a defensive point of view, and Biblical scholars regard the idea that Asa could defeat an enormous Egyptian army to be untenable.