According to the Book of Genesis, Naphtali ("my struggle") was the sixth son of Jacob and second son with Bilhah. He was the founder of the Israelite Tribe of Naphtali. However, some Biblical scholars view this as postdiction, an eponymous metaphor providing an aetiology of the connectedness of the tribe to others in the Israelite confederation. The text of the Torah states that the name of Naphtali refers to the struggle between Rachel and Leah for the favours of Jacob; Bilhah was the handmaid of Rachel, who had thought herself to be infertile, and had persuaded Jacob to have a child with Bilhah as a proxy for having one with herself. 
Tribe of Naphtali
The Tribe of Naphtali was one of the twelve tribes of Israel. In the biblical account, following the completion of the conquest of Canaan by the Israelite Joshua allocated the land among the twelve tribes. Kenneth Kitchen, a well-known conservative biblical scholar, dates this event to slightly after 1200 BCE. However, the consensus view of modern scholars is that the conquest of Joshua as described in the Book of Joshua never occurred.
According to the Bible Joshua assigned Naphtali the eastern side of the Galilee (on the immediate west of the Sea of Galilee), in the areas now known as the Lower Galilee, and Upper Galilee, bordered on the west by Asher, in the north by Dan, in the south by Zebulun, and by the Jordan River on the east. The most significant city was Hazor. In this region, bordering the Sea of Galilee, was the highly fertile plain of Gennesaret, characterised by Josephus as the ambition of nature, an earthly paradise, and with the southern portion of the region acting as a natural pass between the highlands of Canaan, several major roads (such as those from Damascus to Tyre and Acre) ran through it. The prosperity this situation brought is seemingly prophesied in the Blessing of Moses, though textual scholars view this as a postdiction, dating the poem to well after the tribe had been established in the land.
From after the conquest of the land by Joshua until the formation of the first Kingdom of Israel in c. 1050 BC, the Tribe of Naphtali was a part of a loose confederation of Israelite tribes. No central government existed, and in times of crisis the people were led by ad hoc leaders known as Judges (see the Book of Judges). With the growth of the threat from Philistine incursions, the Israelite tribes decided to form a strong centralised monarchy to meet the challenge, and the Tribe of Naphtali joined the new kingdom with Saul as the first king. After the death of Saul, all the tribes other than Judah remained loyal to the House of Saul, but after the death of Ish-bosheth, Saul's son and successor to the throne of Israel, the Tribe of Naphtali joined the other northern Israelite tribes in making David, who was then the king of Judah, king of a re-united Kingdom of Israel. However, on the accession of Rehoboam, David's grandson, in c. 930 BC the northern tribes split from the House of David to reform a Kingdom of Israel as the Northern Kingdom.
In c. 732 BCE, Pekah allied with Rezin, king of Aram, threatened Jerusalem, and Ahaz, king of Judah, appealed to Tiglath-Pileser III, the king of Assyria, for help. After Ahaz paid tribute to Tiglath-Pileser, (2 Kings 16:7-9) Tiglath-Pileser sacked Damascus and Israel, annexing Aram and a large part of Israel, "including all the land of Naphtali." According to 2 Kings 16:9 and 15:29, the population of Aram and the annexed part of Israel was deported to Assyria. The kingdom of Israel continued to exist until c. 723 BC, when it was again invaded by Assyria and the rest of the population deported.
From that time, the Tribe of Naphtali has been counted as one of the Ten Lost Tribes of Israel.