I think your best, and maybe only, solution is to take the car to your Lexus dealership in Bahrain and have them order and install the Middle East map you need for your location.

I don't know what year your GS 350 is, but I suspect the process to change an installed map (from North America to the Middle East) is about the same as installing map updates. First, the Lexus dealership orders the map from Lexus corporate, tags the map with your car's VIN number for which it will be installed. Then, Lexus corporate releases the map for the Lexus dealership to download the map from Lexus corporate's server. Once the map is downloaded to the dealership's computer it is available for a technician to install specifically to your vehicle's navigation system.

The process for your local Lexus dealership to order and receive the map from Lexus corporate can take anywhere from under an hour (if lucky) to a few days, depending on if the order is placed after hours or on a weekend and how busy corporate staff is and their server load. I think some dealerships order the map or map update days in advance of the customer's service date, designating the map to the vehicle's VIN number - and then calling the customer when they actually receive the map for you to come in and have it installed.

Depending on the model year of your GS 350 the process (once the dealership has the map on their computer that is dedicated specifically for your vehicle) is to have a technician load the map on a laptop computer or memory device and install it to your vehicle's navigation system. This is done by starting the vehicle's engine and leaving it running the entire time during the map install. It usually takes the technician just under an hour from start to finish.

I rather doubt you can get what you need by any means other than your local Lexus dealership in Bahrain...