The move reflects Yahoo's desire to rival Google at Internet domination and get into emerging markets.
The Sunnyvale company said that although there are some 320 million Arabic speakers in the world, less than 1 percent of all online content is in that language.
Maktoob is based in Amman, Jordan.
Since launching in 1998, the Maktoob group has expanded to include an Arabic search engine, travel portal, games, online market place and electronic payment system. These other businesses are not part of the Yahoo deal. No word on the price tag for Yahoo's aquisition.
Early in its history, Yahoo expanded through joint ventures, later buying back some sites. More recently, it sold Yahoo China to Alibaba, a Chinese Internet company. It owns a large stake in Yahoo Japan but does not control it. Google, which has full control over its overseas websites, has been more successful than Yahoo in Europe and China -- more battlefields on which the search giant has been dealing Yahoo a drubbing.