"At first, Fulla was developed to have long coal black hair streaked with auburn and brown eyes, but later, dolls with lighter hair and eyes were introduced. The product development team considered about 10 different faces before deciding on her look. She was dressed in a black abaya and head scarf for the Saudi market, but no veil in other markets; because the product development didn’t want to "go to extremes." For more liberal countries, Fulla has a white scarf and pastel coat. Her outdoor clothes have since become more colorful, but her shoulders are always covered and the skirt always falls below her knees, as traditionally Muslim women are expected to dress conservatively. She can also be found wearing half- and quarter-sleeve dresses, but not sleeveless." (Wikipedia)
Apparently the product was developed in response to the banning of Barbie in some Muslim countries, especially Saudi Arabia.