The REGION dimension is a typical Type I SCD dimension. If some description changes, it makes no sense to keep the old values. The new values simply overwrite the old ones. Sometimes you would like to keep a history of the changes. This is when Type II Slowly Changing Dimensions come into play. A Type II SCD keeps the whole history of the data of your dimension. Some typical examples of attributes for which you would like to keep history are sales territories that change over time, categories of products that are reclassified from time to time, promotions that you apply to products, which are valid in a given range of dates.
There are no rules that dictate whether or not you keep the ...
