Duke is a title for a high-ranking nobleman that has been known through much of Europe (in Latin dux, in French duc etc.) for centuries, including in England where The King James Bible (see also The King James Preface) was translated in 1611. The King James translators used "duke" for the original Hebrew word of the Scriptures, pronounced al-oof, denoting a chief, or governor.
The King James uses "duke" where later translations of the Bible use "chief:"
"These were dukes of the sons of Esau: the sons of Eliphaz the firstborn son of Esau; duke Teman, duke Omar, duke Zepho, duke Kenaz, Duke Korah, duke Gatam, and duke Amalek: these are the dukes that came of Eliphaz in the land of Edom; these were the sons of Adah."
"And these are the sons of Reuel Esau's son; duke Nahath, duke Zerah, duke Shammah, duke Mizzah: these are the dukes that came of Reuel in the land of Edom; these are the sons of Bashemath Esau's wife."
"And these are the sons of Aholibamah Esau's wife; duke Jeush, duke Jaalam, duke Korah: these were the dukes that came of Aholibamah the daughter of Anah, Esau's wife."
"These are the sons of Esau, who is Edom, and these are their dukes." (Genesis 36:15-19 KJV)
The Promised Land:
"The people shall hear, and be afraid: sorrow shall take hold on the inhabitants of Palestina."
"Then the dukes of Edom shall be amazed; the mighty men of Moab, trembling shall take hold upon them; all the inhabitants of Canaan shall melt away. Fear and dread shall fall upon them; by the greatness of Thine arm they shall be as still as a stone; till Thy people pass over, O Lord, till the people pass over, which Thou hast purchased. Thou shalt bring them in, and plant them in the mountain of Thine inheritance, in the place, O Lord, which Thou hast made for Thee to dwell in, in the Sanctuary, O Lord, which Thy hands have established." (Exodus 15:14-17 KJV)
Fact Finder: What was the actual origin of the term "Palestina" as noted in Exodus 15:14, above?
See The Truth About Israel and the "Palestinians"