I installed Arabic support in Ubuntu 12.04 but there is no Arabic Saudi Arabia in Regional Formats list. All other Arabic regional formats are available e.g. Arabic UAE, Arabic Syria, Arabic Kuwait, Arabic Bahrain etc but not Arabic Saudi Arabia !
If you have Arabic language added to the list of system languages
You will have the option to choose Arabic SA from the regional format Tab as seen below
Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the commands below.
The following workaround solved the problem for me (on both systems): I removed Arabic support, re-installed it, and Arabic Saudi Arabia has now appeared in Regional Formats list.