according to the Bible he was a king of salem but there aren't more information about him in the book of genesis but are there more information in the jewish tradition?
First, notice from both Old and New Testaments that the man of mystery, Melchizedek, was a priest of the Most High God. Turn 'low to the account in Genesis 14. During the war between a number of ancient city-states in Canaan and Mesopotamia, Abraham's nephew Lot had been captured. He and his family and goods were carted off.
One of their number escaped and brought the news to Abraham, who armed 318 of his own servants and pursued the invaders to what was later named Dan and beyond. Abraham rescued Lot and his family and returned them safely to the Canaanite cities.
On Abraham's return a man of mystery bursts upon the scene. Abraham was ministered to by Melchizedek.
Here is the account:
"And Melchizedek king of Salem brought out bread and wine; he was priest of God Most High. And he [Melchizedek] blessed him [Abraham] and said, 'Blessed be Abram by God Most High, maker of heaven and earth; and blessed be God Most High, who has delivered your enemies into your hand!' And Abram gave him [Melchizedek] a tenth of everything" that is, a tithe of all, for a tithe means a tenth (Genesis 14:18-20, RSV).
Notice that Melchizedek was king of Salem. That is the city of Jerusalem. "Salem" comes from the Hebrew word meaning "peace." That would make Melchizedek the "King of Peace" (Hebrews 7:2). The Hebrew name Melchizedek itself means "King of Righteousness" (Hebrews 7:2). The same individual is mentioned in Psalm 110:4. Speaking prophetically of Christ, David stated: "The Eternal hath sworn, and will not repent, Thou art a priest forever after the order of Melchizedek." This verse is quoted again in Hebrews 5:6, 10.
Before we turn to Hebrews for the identification of Melchizedek, remember that this mystery figure is a mystery only to us. Abraham and the King of wicked Sodom knew exactly who he was. They must have seen him before. He could not have been a Canaanite, for they were steeped in pagan customs. And furthermore Canaan was a descendant of Ham, whereas God basically chose the descendants of Shem to accomplish His work.