Melchizedek is only mentioned three times in the Bible and seems to be a mystery, until you study the life of Shem, the most honored son of Noah. And the fact that Abraham descended from Shem.
Genesis 14:18-19
Then Melchizedek king of Salem brought our bread and wine, He was priest of God Most High, and he blessed Abram, saying “Blessed be Abram by God Most High, Creator of heaven and earth. (NIV)