The Lost Tribe of Gad is modern Spain and all other affiliated countries.
Jacob's pronouncement over Gad:
1 Genesis 49:19
19¶Gad, a troop shall overcome him: but he shall overcome at the last.
The term raider would end up as the Spanish term conquistador and is best know as the Spanish gallions that raided Central and South American for what would be known as Spanish Gold.
Gad ended up with a considerable inheritance, including all of Central and South America.
The Treaty of Nijmegen forms the seal date document for Gad, and identifies Gad as Spain.
Curiously, on the exact seal date, a French fleet is sunk by Dutch ships in the Carribean, which is Gad's territory.