Alfonso X of Castile vs Esen Taishi

Alfonso X commissioned the Alfonsine Tables, a set of astronomical tables based on Ptolemaic models. These tables were used by European astronomers for centuries and became a standard reference in medieval science.

Alfonso X of Castile was elected King of Germany by a faction of prince-electors, opposing Richard of Cornwall. This election was part of the Great Interregnum, with Alfonso receiving support from the Hohenstaufen loyalists and the Papacy.

Alfonso X never traveled to Germany to assert his claim to the throne. His absence weakened his authority, and he was unable to secure effective control over the German kingdom, leaving the title contested.

Alfonso X formally renounced his claim to the German throne in favor of Rudolf of Habsburg. This renunciation ended the Great Interregnum and allowed Rudolf to be recognized as the legitimate king of Germany.

Esen Taishi led the Oirat Mongols to victory at the Battle of Tumu Fortress, capturing the Ming emperor Zhengtong. This event shocked the Ming dynasty and demonstrated Oirat military power, though Esen failed to capitalize on the victory.

Esen Taishi proclaimed himself khan of the Mongols, claiming the title of Great Khan. This move alienated many Mongol nobles and led to internal conflict, weakening his position.

Esen Taishi was assassinated by former allies, ending his rule. His death led to the decline of Oirat power and the fragmentation of the Mongol confederation.