Gambling (qimar) is strictly forbidden by Islamic law on the basis that it represents an exchange of property that is neither productive nor sanctioned and is thus a frivolous and useless business transaction. Moreover, gambling also prevents Muslims from performing their obligations of prayer and worship and has the potential to lead to arguments and violence. Despite legal injunctions against the practice, gambling did occur throughout the medieval Islamic world at all levels of society. It may be divided into two broad categories. The first sort of gambling consisted of board games such as nard (backgammon), chess, throwing dice, casting lots, cards, guessing games, and manqalah (the game of fourteen). The other kind of gambling was the placing of stakes on sports. The most common sports involving stakes were horse and camel racing, swimming, archery, wrestling, foot racing, pigeon flying, and polo. Gambling on sporting events usually took place in large open spaces, whereas game playing with stakes generally occurred in private. Large cities often housed gambling establishments or casinos, and some even offered gamblers the allure of on-site loans to continue their play. Legal authorities tended to ignore gambling unless it caused a disturbance to neighboring residents or businesses in the form of noise, crime, or disorder.