Andalusian Arabic appears to have spread rapidly and been in general oral use in most parts of Al-Andalus between the 9th and 15th centuries. The number of speakers is estimated to have peaked at around 5–7 million speakers around the 11th and 12th centuries before dwindling as a consequence of the Reconquista, the gradual but relentless takeover by the Christians. The colloquial Arabic of al-Andalus was prominent among the varieties of Arabic of its time in its use for literary purposes, especially in "zajal" poetry and proverbs and aphorisms.