Knucklebones is another name for the game of jacks, the popular children's game. These days, it is usually played with small, die-cast metal pieces, but in the past, it was played with actual knuckle bones from the foot of a sheep or goat.
Gambling with knuckle bones has been documented throughout recorded history, and by the time of the Romans, it was practically an institution. Tali is the Roman name for a set of four knucklebones used for gambling. Archeologists have recovered tali made from semi-precious stone, glass, pottery, and metal.
Knuckle bones are somewhat cubical, but slightly elongated with two rounded ends. Think of a modern, six-sided die with two of its opposing faces rounded outwards. Consequently, when a kunckle bone is dropped onto a flat surface, it will come to rest with one of the four flat surfaces upwards. Because of anatomical considerations, these four surfaces have an unequal chance of appearing on every throw of the bones. To combat this bias, the ancients numbered the faces with either a one, three, four or six. When four bones are thrown simultaneously, the sum total of the numbers displayed by each face is virtually random. Through trial and error, the ancients worked out the ratio needed to turn the decidedly un-random knuckle bones into a gambling tool.
While the tali, and the games played with them were mentioned countless times in ancient texts, the details of the rules for the actual games played with the tali are lost to the sands of time. However, it is accepted that a throw resulting in a different face showing on all four bones would win you the pot. Generally, players would add money to the pot every time they threw certain unlucky combinations, and whoever managed to roll the lucky combination, usually named after Venus, would win the pot.