What does the "TerritoryName (47)" number mean?

[Eressil3]

It's usefull for diplomacy in MP

"Give me 47 and I let you in 52".

In MP you can ask to an ally to cast a nasty spell you don't have on the specific province of your choice. Since your ally may not read its name, the only way is give the number.

[paradoxharbinger]

it is the id number for the province. they are numbered according to thier position on the map, starting in the bottom left corner and then going across the map. when the edge is hit, go back to the left and up one pixel. everytime you hit a province center, increase the id number. so province number 47 would indicate the 47th province encountered this way.