Saudi Arabia
Saudi Arabia, ever since the influx of the Wahabi ideology, has become incredibly strict especially with rules regarding women, such as the fact that they are not allowed to drive cars. Therefore, it is no surprise that Saudi Arabia is one of the countries where the hijab is mandatory for foreigners. While most women cover their entire face, many chose a simple hijab, which leaves their face uncovered.
That being said, these were the two countries where hijab is mandatory for foreigners.