Context: The Northern Crusades provided a rationale for the growth and expansion of the Teutonic Order of German crusading knights which had been founded in Palestine at the end of the 12th century. Due to Muslim successes in the Holy Land, the Order sought new missions in Europe. Duke Konrad I of Masovia in west-central Poland appealed to the Knights to defend his borders and subdue the pagan Baltic Prussians in 1226. After the subjugation of the Prussians, the Teutonic Knights fought against the Grand Duchy of Lithuania. When the Livonian knights were crushed by Samogitians in the Battle of Saule in 1236, coinciding with a series of revolts in Estonia, the Livonian Order was inherited by the Teutonic Order, allowing the Teutonic Knights to exercise political control over large territories in the Baltic region. Mindaugas, the King of Lithuania, was baptised together with his wife after his coronation in 1253, hoping that this would help stop the Crusaders' attacks, which it did not. The Teutonic Knights failed to subdue pagan Lithuania, which officially converted to  Christianity in 1386 on the marriage of Grand Duke Jogaila to the 11-year-old Queen Jadwiga of Poland. However, even after the country was officially converted, the crusades continued up until the Battle of Grunwald in 1410, when the Lithuanians and Poles, helped by the Tatars, Moldovans and the Czechs, defeated the Teutonic knights. The Teutonic Order's attempts to conquer Orthodox Russia , an enterprise endorsed by Pope Gregory IX, accompanied the Northern Crusades. One of the major blows for the idea of the conquest of Russia was the Battle of the Ice in 1242. With or without the Pope's blessing, Sweden also undertook several crusades against Orthodox Novgorod.

Question: How many groups helped the Lituanians and the Poles defeat the Teutonic knights?

Answer:
3