A HUNDRED was an early designation for an adminstrative land division during British colonial settlement. A Hundred would be created when a 100 people had settled in a given area. A Hundred was established with a constable and was followed by a court system. It was given a distinct name, such as Sugar Loaf Hundred, Pipe Creek Hundred, Monocacy Hundred, etc. as we see in colonial Pennsylvania, Maryland, and other places. The term is still used in Delaware today.
When first established, a Hundred probably consisted of a greater land area. As time passed, population increased, more Hundreds were created. As these new Hundreds were formed they would decrease in size just as counties and townships did in early America. As Hundreds were reformed and/or resurveyed, they, too, would decrease in mass size. (A "Hundred" may well be similiar to the townships one finds in Pennsylvania, today.) These Hundreds were later replaced with districts which usually were named after the town that it included and/or a district number.
Regarding land tract names: Tracts many times started out with hundreds of acres and later were divided off and sold to different people. When an area was resurveyed (perhaps including parts of several different tracts), it many times was given a new tract name. So, a land tract by one name may have been part of an earlier land tract by a different name. This can be noticed when referring to equity court abstracts of a given county.