The tribes of Gad and Reuben, two of the twelve tribes of Israel, are descendants of Jacob's sons Gad and Reuben. These tribes are often mentioned together in the Old Testament due to their shared history and geographical proximity.

Reuben:

Reuben was the firstborn son of Jacob and Leah. As the firstborn, Reuben was initially entitled to a double portion of inheritance and leadership within the family. However, due to his transgression with Bilhah, his father's concubine, he lost his birthright. Genesis 35:22 records this incident: "While Israel was living in that region, Reuben went and slept with his father’s concubine Bilhah, and Israel heard of it."

Despite this, the tribe of Reuben played a significant role in the history of Israel. In the wilderness, the tribe was counted among the fighting men of Israel, numbering 46,500 (Numbers 1:21). Reuben's descendants settled on the east side of the Jordan River, in the land of Gilead, which was suitable for their large herds and flocks.

Gad:

Gad was the seventh son of Jacob and the firstborn of Zilpah, Leah's maidservant. The tribe of Gad was known for its valor and military prowess. In the wilderness, the tribe of Gad was counted at 45,650 fighting men (Numbers 1:25). Like Reuben, the tribe of Gad also settled on the east side of the Jordan River.

The land allotted to Gad was known for its fertile pastures, which were ideal for their livestock. The tribe of Gad was characterized by its warrior spirit, as noted in 1 Chronicles 12:8: "Some Gadites defected to David at his stronghold in the wilderness. They were brave warriors, ready for battle and able to handle the shield and spear. Their faces were the faces of lions, and they were as swift as gazelles in the mountains."

Joint Settlement:

The tribes of Reuben and Gad, along with the half-tribe of Manasseh, requested to settle in the land of Gilead, east of the Jordan River, because it was suitable for their livestock. Numbers 32:1-5 describes their request: "The Reubenites and Gadites, who had very large herds and flocks, saw that the lands of Jazer and Gilead were suitable for livestock. So they came to Moses and Eleazar the priest and to the leaders of the community, and said, 'Ataroth, Dibon, Jazer, Nimrah, Heshbon, Elealeh, Sebam, Nebo and Beon—the land the LORD subdued before the people of Israel—are suitable for livestock, and your servants have livestock. If we have found favor in your eyes,' they said, 'let this land be given to your servants as our possession. Do not make us cross the Jordan.'"

Moses initially objected, fearing that their decision would discourage the other Israelites. However, the tribes of Reuben and Gad promised to assist in the conquest of Canaan before returning to their allotted land. Numbers 32:16-18 records their commitment: "Then they came up to him and said, 'We would like to build pens here for our livestock and cities for our women and children. But we will arm ourselves for battle and go ahead of the Israelites until we have brought them to their place. Meanwhile, our women and children will live in fortified cities, for protection from the inhabitants of the land. We will not return to our homes until each of the Israelites has received their inheritance.'"

Historical Significance:

The tribes of Gad and Reuben played a crucial role in the early history of Israel. Their settlement on the east side of the Jordan River set a precedent for the division of the land among the tribes. Their commitment to assist in the conquest of Canaan demonstrated their loyalty to the larger community of Israel.

Throughout the biblical narrative, the tribes of Gad and Reuben are depicted as integral parts of the nation of Israel, contributing to its military strength and agricultural prosperity. Their account is a testament to the complex dynamics of tribal identity, inheritance, and faithfulness within the covenant community of Israel.