Fire Emblem: The Age of Legend
House of Yeor
Yeor is not a particularly notable place, by the standards of people in countries like Peruvia it might well be considered a poor and desolate area, but it was just fine for what was then part of the Northern Principalities.
While Yeorians are likely to credit the personal genius of King Dinmerfin as what allowed the country to be unified from dozens of petty principalities around 2A 3049, historians are often inclined to see it as the result of a much longer and slower process. Yeoria had good natural harbors and decent access to timber, it was therefore able to tap into the trade around the Sea of Rove, bringing in money. It was very hard to invade, being surrounded by water, and so they did not have to spend money on defense and frequent rebuilding. Eventually they simply built up a full enough treasury that they could afford to pay or hire many soldiers, give substantial rewards to allies, pay any needed ransoms, and otherwise fully fund their conquest. That King Dinmerfin was a very diplomatically canny man who drew to him many willing allies like Tollidarius VIII of the House of Ivla as well as an apt military commander helped as well though.
What really made Yeoria succeed as a country was that Dinmerfin lived to ripe old age and was thereby able to solidify his holdings and pass them on to his son, King Twemornir of Yeoria, and through him on to others of the House of Yeor for generations to come.
Only now in 2A 3214, the present day, is this control being seriously challenged.