Risbridge Hundred forms the southwestern corner of Suffolk extending 15 miles (24 km) from north to south and between 4 and 9 miles (14 km) in breadth. It is bounded on the west by Cambridgeshire on the south by Essex, on the east by Babergh and Thingoe Hundreds and on the north by Lackford Hundred. It is in the Franchise or Liberty of St Edmund, in the Archdeaconry of Sudbury, Deanery of Clare and Diocese of Ely.
The southern boundary with Essex is formed by the River Stour and the hundred is crossed by a number of streams. It is generally a fertile agricultural area with predominantly clay soil. The major towns in the hundred are Clare and Haverhill.
Listed as Risebruge in the Domesday Book, the meaning of the name is not fully understood but probably "Hrisa's bridge" or a similar personal name. The bridge in question would almost certainly have crossed the Stour, an important crossing at a time when bridges were rare.
Wikipedia provides a map of The Hundreds of Suffolk.