By region option lets you plot records on the map based on the region of your choice.
The various regions that you can select one from are City, State, Country, and Postal Code. 
If you select the State, you need to insert the ‘State’ name for that you need to check the records on the map.
User can also plot multiple regions in map by adding comma (,) separated values. For example: Texas, Tennessee. 
Now, by clicking on the Search button, only the inserted states get highlighted on map along with the records that come under that states. 
By clicking on any shape, it will display Summary Card for selected shape. 
You can see details in the Summary Card of the selected State.
By clicking on the close X icon, the state will deselect.
You can also manage the Territory when the Region search option is selected and records are plotted on the map.
By right-clicking on the Region (plotted location/area), you will get the option to for the Territory to create or manage. 
You will get the “Create New Territory” popup from where you can add the selected region to existing territory, or you can create a new Territory.
You will get some analytics that how many records of Accounts, Contacts & Leads on that region. After selecting any option, click on the Save button to add the selected region into the Territory. 
Note: You can create and manage the Territory from the individual option of the “Territory Management”.