Vasco da Gama was born in 1460 or 1469 in Sines, on the southwest coast of Portugal, probably in a house near the church of Nossa Senhora das Salas. Sines, one of the few seaports on the Alentejo coast, consisted of little more than a cluster of whitewashed, red-tiled cottages, occupied chiefly by fisherfolk. Vasco da Gama's father was Estevao da Gama, who had served in the 1460s as a knight of the household of Infante Ferdinand, Duke of Viseu. He rose in the ranks of the military Order of Santiago.

In December 1499, King Manuel I of Portugal rewarded Vasco da Gama with the town of Sines as a hereditary fief (the town his father, Estevao, had once held as a commenda). This turned out to be a complicated affair, for Sines still belonged to the Order of Santiago. The master of the Order, Jorge de Lencastre, might have endorsed the reward - after all, da Gama was a Santiago knight, one of their own, and a close associate of Lencastre himself. But the fact that Sines was awarded by the king provoked Lencastre to refuse out of principle, lest it encourage the king to make other donations of the Order's properties. Da Gama would spend the next few years attempting to take hold of Sines, an effort that would estrange him from Lencastre and eventually prompt da Gama to abandon his beloved Order of Santiago, switching over to the rival Order of Christ in 1507.  In the meantime, da Gama made do with a substantial hereditary royal pension of 300,000 reis. He was awarded the noble title of Dom (lord) in perpetuity for himself, his siblings and their descendants. On 30 January 1502, da Gama was awarded the title of Almirante dos mares de Arabia, Persia, India e de todo o Oriente ("Admiral of the Seas of Arabia, Persia, India and all the Orient") - an overwrought title reminiscent of the ornate Castilian title borne by Christopher Columbus (evidently, Manuel must have reckoned that if Castile had an 'Admiral of the Ocean Seas', then surely Portugal should have one too). Another royal letter, dated October 1501, gave da Gama the personal right to intervene and exercise a determining role on any future India-bound fleet.  Around 1501, Vasco da Gama married Catarina de Ataide, daughter of Alvaro de Ataide, the alcaide-mor of Alvor (Algarve), and a prominent nobleman connected by kinship with the powerful Almeida family (Catarina was a first cousin of D. Francisco de Almeida). Answer this question using a quote from the following article:

What is the origin of this title?
an overwrought title reminiscent of the ornate Castilian title borne by Christopher Columbus (