Leaders known among the people
In Numbers 11, Moses feels crushed by the constant demands and complaints of the vast Israelite camp. God does not tell Moses simply to try harder. Instead, He tells him to gather seventy men from the elders of Israel, men Moses already knew to be elders and officers among the people (Numbers 11:16 KJV).
An elder was usually a mature, respected leader within a family group, tribe, or town. These men had some recognised responsibility before this moment. God was appointing them to a new shared task alongside Moses, not making them replacements for him.
And the Lord said unto Moses, Gather unto me seventy men of the elders of Israel, whom thou knowest to be the elders of the people, and officers over them; and bring them unto the tabernacle of the congregation, that they may stand there with thee. And I will come down and talk with thee there: and I will take of the spirit which is upon thee, and will put it upon them; and they shall bear the burden of the people with thee, that thou bear it not thyself alone.
They shared Moses' burden
The central purpose was practical: the elders would help carry the weight of governing Israel. Moses had been leading a people recently freed from Egypt, travelling through the wilderness, settling disputes, and hearing their needs. Seventy leaders meant that the care of the community would not rest on one exhausted man alone (Numbers 11:17 KJV).
This fits an earlier pattern in Israel. Moses had already been told to choose capable men to serve as rulers over groups of people and to bring only the hardest cases to him (Exodus 18:21-22 KJV). Shared leadership was not a sign of Moses' failure. It was wise provision.
God's Spirit came upon them
After Moses gathered the elders at the tabernacle, the Lord took of the Spirit that was upon Moses and placed it upon them. This does not mean Moses received less of God's help. It means God equipped these men for the same work of serving His people (Numbers 11:24-25 KJV).
They prophesied when the Spirit rested on them. In this setting, their prophecy was a public sign that God had genuinely authorised them. Two men, Eldad and Medad, also received the Spirit in the camp, even though they had not gone out to the tabernacle. Moses welcomed this rather than treating it as a threat (Numbers 11:26-29 KJV).
And Moses went out, and told the people the words of the Lord, and gathered the seventy men of the elders of the people, and set them round about the tabernacle. And the Lord came down in a cloud, and spake unto him, and took of the spirit that was upon him, and gave it unto the seventy elders: and it came to pass, that, when the spirit rested upon them, they prophesied, and did not cease.
Were they the Sanhedrin?
The Bible also mentions seventy elders with Moses, Aaron, Nadab, Abihu, and others at Mount Sinai, where they were allowed to worship from a distance and witnessed a remarkable revelation of God's glory (Exodus 24:1, 9-11 KJV). They may have been the same kind of national leaders, though the text does not give a full list of names or clearly trace every individual.
Some later Jewish tradition connected Moses' seventy elders with the Sanhedrin, the Jewish council known from the time of Jesus. But Numbers does not call these wilderness leaders the Sanhedrin. Its main point is simpler and encouraging: God cared for Israel by raising up faithful people to serve together, and He supplied what they needed for the task.
But there remained two of the men in the camp, the name of the one was Eldad, and the name of the other Medad: and the spirit rested upon them; and they were of them that were written, but went not out unto the tabernacle: and they prophesied in the camp. And there ran a young man, and told Moses, and said, Eldad and Medad do prophesy in the camp. And Joshua the son of Nun, the servant of Moses, one of his young men, answered and said, My lord Moses, forbid them. And Moses said unto him, Enviest thou for my sake? would God that all the Lord's people were prophets, and that the Lord would put his spirit upon them!