Given the task definition and input, reply with output. Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: The Battle of al-Qadisiyyah (Arabic: ; transliteration, Ma'rakatu al-Qadisiyyah; Persian: transliteration Nabard-e Qadesiyeh; alternative spellings: Qadisiyya, Qadisiyyah, Kadisiya, Ghadesiyeh), fought in 636, is said to be a decisive engagement between the Arab Muslim army and the Sassanid Persian army during the first period of Muslim expansion.
Question: On what date did Battle of al-Qadisiyyah end?
636