Henry III of Castile sends Ruy González de Clavijo as ambassador to Timur to discuss the possibility of an alliance between Timur and Castile against the Ottoman Empire.

Henry III of Castile
Henry III of Castile, called the Suffering due to his ill health, was the son of John I and Eleanor of Aragon. He succeeded his father as King of Castile in 1390.
Ruy González de Clavijo
Ruy González de Clavijo was a Castilian traveler and writer. In 1403–05 Clavijo was the ambassador of Henry III of Castile to the court of Timur, founder and ruler of the Timurid Empire. A diary of the journey, perhaps based on detailed notes kept while traveling, was later published in Spanish in 1582 and in English in 1859.
Timurid relations with Europe
Timurid relations with Europe developed in the early 15th century, as the Persianate Turco-Mongol ruler Timur and European monarchs attempted to operate a rapprochement against the expansionist Ottoman Empire. A strong hostility remained between the Timurds and the Ottoman Turks as well as the Egyptian Mamluks.
Ottoman Empire
The Ottoman Empire, also called the Turkish Empire, was an imperial realm that controlled much of Southeast Europe, West Asia, and North Africa from the 14th to early 20th centuries; it also controlled parts of southeastern Central Europe, between the early 16th and early 18th centuries.