With the signing of the Treaty of Zamora, King Alfonso VII of León and Castile recognises Portugal as a Kingdom.

The Conference of Zamora was a diplomatic meeting held on 4–5 October 1143 between Afonso Henriques, then styled Infante of Portugal, and his cousin Alfonso VII of León, King of León and Castile. It took place at the Cathedral of Zamora in the presence of the papal legate, Cardinal Guido de Vico. While often erroneously referred to as the "Treaty of Zamora," no surviving document from the meeting supports the conclusion that a formal treaty recognizing Portugal's independence was signed at this time.

Alfonso VII, called the Emperor, became the King of Galicia in 1111 and King of León and Castile in 1126. Alfonso, born Alfonso Raimúndez, first used the title Emperor of All Spain, alongside his mother Urraca, once she vested him with the direct rule of Toledo in 1116. Alfonso later held another investiture in 1135 in a grand ceremony reasserting his claims to the imperial title. He was the son of Urraca of León and Raymond of Burgundy, the first of the House of Ivrea to rule in the Iberian Peninsula.

October 5 is the 278th day of the year in the Gregorian calendar; 87 days remain until the end of the year.