Aleppo was bred in Yorkshire by John Brewster, prior to his marriage to Jane Darley. A tradition in the Darley family is that Aleppo was a chesnut, although most of the old authorities say that he was a bay. In 1716 he won the £30 Ladies' Plate for 5 year olds at York, over four miles. In 1717 he finished 3rd in His Majesty's Gold Cup for six year olds at York. In 1719 he finished 2nd in a £40 Plate for aged horses at York, in three 4-mile heats. Purchased by Mr Bawtry, he retired to stud.