I have tried to follow the genealogies of Wiki and Britannica and get lost in the II's and III's and brothers and half brothers. I choose instead to to follow two other sites mainly when matters confuse: http://www.donlinke.com/drakula/vlad.htm
This son Vlad II Dracul son of Vlad I joined the Society of Dragonists in Luxembourg in about 1431, of Wallachia. He had three sons Mircea, the eldest; then Vlad III Dracul who became the Impaler or Tepes, and a younger son, Radu. See http://www.donlinke.com/drakula/vlad.htm.
More detail on their lives: see https://www.romaniaroadwaysvladtepes.blotspot.com.
Although most timelines begin with Luxembourg in 1914, look into history for origins: founded in 963. A portion of Luxembourg known as Belgium became part of the Netherlands. See http://www.worldatlas.com/webimage/countrys/europe/luxembourg/lutimeln.htm
1378-1400 -- Wenceslas, King of the Romans, ruled the House of Luxembourg, see https://en.wikipedia.org/wiki/List_of_state_leaders_in_1387#Europe
Vianden Castle, mountain view, Luxembourg
1408 -- Sigismund, 1387-1437 , King of Hungary and then Holy Roman Emperor, then became Sigismund of Luxembourg.
1410 --- Sigismund of Luxembourg founded an Order similar to the Crusading orders, the Order of the Dragon, the Society of the Dragonists, here see https://en.wikipedia.org/wiki/Order_of_the_Dragon.
Best history of the region, in short: See http://www.donlinke.com/drakula/vlad.htm
- Inter-group involvements. Janos Hunyadi: among the first rulers to maintain a standing army rather than rely on feudal levies. Hired Czechs, Serbs, veterans. See site. Crossed the Danube, into Serbia (Sofia is now Bulgaria) to fortified Turkish garrisons. Got to the Balkans, were forced back by winter weather, and regrouped in Buda, Montenegro.