King Melchizedek
Melchizedek was the King of Salem.
Melchizedek in Hebrew means: my king is righteous.
Melchizedek's city Salem in Hebrew means: Peace.
Jebusites named the city Jebus and later the two names were joined to make Jerusalem in Hebrew means: Habitation of peace.
Abraham presented Melchizedek with a tithe (a tenth) of all the booty he had gathered. By this act Abraham indicated that he recognized Melchizedek as a fellow-worshiper of the one true God as well as a priest who ranked higher spiritually than he did.
Melchizedek's existence shows that there were people other than Abraham and his family who served the true God.
Background Reading:
Genesis 14:18-20
Melchizedek
18 Then Melchizedek king of Salem brought out bread and wine. He was priest of God Most High, 19 and he blessed Abram, saying,
"Blessed be Abram by God Most High,
Creator of heaven and earth.
20 And blessed be God Most High,
who delivered your enemies into your hand."
Then Abram gave him a tenth of everything.