The Sanjiegun, Sansetsukon or three sectional staff , is a Chinese flail weapon that consists of three wooden or metal staffs connected by metal rings or rope. A larger, more complicated version of the well-known nunchaku, the staffs can be spun to gather momentum resulting in a devastating strike, or their articulation can be used to strike over or around a shield or other defensive block. It is also known as the "Sansetsukon" in Japanese.

These staffs were designed for defence against spears and other long weapons. Historically made of white oak or Chinese red maple, modern staffs are constructed from rattan, bamboo, various hardwoods or aluminium. For optimum fit, each of the three sticks should be about the length of the combatant’s arm and have a combined diameter that easily fits in the hand.

The total length of the weapon is greater than that of the short single staff known in Japanese as a bo, about the same as the Chinese staff, the gun, creating a larger circle of available targets around the combatant. Many of the techniques are similar to that of the staff, so spinning moves over the head and behind the back can be practiced with a regular staff. The three sectional staff has the advantage of being used both as a long-range weapon or a short-range weapon. Acting as an extension of the users arm, the three sectional staff can strike, block, stab, sweep legs and whip, often with different sections of the staff acting at the same time. The chains or binding ropes of the staff are used to entangle an opponent and their weapons.

Carrying or even owning a three sectional staff is prohibited in many jurisdictions.

Historical accounts of the three sectional staff

The first written account of the three sectional staff is found in the literary work known as the Sanguo Zhi, also known by its English name Records of the Three Kingdoms.