between Turk and Tajik became stereotyped to express the symbiosis and rivalry of the (ideally) nomadic military executive and the urban civil bureaucracy (Niẓām al-Molk: tāzik, pp. 146, 178–79; Fragner, "Tādjīk. 2" in EI2 10, p. 63). The word also occurs in the Tonyukuk inscriptions as tözik, used for a local Arab tribe in the Tashkent area. These Arabs were said to be from the Taz tribe, which is still found in Yemen. In the 7th-century, the Taz began to Islamize Transoxiana. According to the Encyclopaedia of Islam, however, the oldest known usage of the word Tajik as a reference to Persians in Persian literature can be found in the writings of the Persian poet Jalal ad-Din Rumi. The 15th-century Turkic-speaking poet Mīr Alī Šer Navā'ī also used Tajik as a reference to Persians. Location The Tajiks are the principal ethnic group in most of Tajikistan, as well as in northern and western Afghanistan, though there are more Tajiks in Afghanistan than in Tajikistan. Tajiks are a substantial minority in Uzbekistan, as well as in overseas communities. Historically, the ancestors of the Tajiks lived in a larger territory in Central Asia than now. Tajikistan Tajiks make up around 84.3% of the population of Tajikistan. This number includes speakers of the Pamiri languages, including Wakhi and Shughni, and the Yaghnobi people who in the past were considered by the government of the Soviet Union nationalities separate from the Tajiks. In the 1926 and 1937 Soviet censuses, the Yaghnobis and Pamiri language speakers were counted as separate nationalities. After 1937, these groups were required to register as Tajiks. Afghanistan According to the World Factbook, Tajiks make up about 27% of the population in Afghanistan, but according to other sources, they form 37%–39% of the population. According to the Encyclopædia Britannica they constitute about one-fifth of the population. They are predominant in four of the largest cities in Afghanistan (Kabul, Mazar-e Sharif, Herat, and Ghazni) and make up the largest ethnic group in the northern and western provinces of Balkh, Takhar, Badakhshan, Samangan, Parwan, Panjshir, Kapisa, Baghlan, Ghor, Badghis and Herat. In Afghanistan, the Tajiks do not organize themselves by tribes and refer to themselves by the region, province, city, town, or village that they are from; such as Badakhshi, Baghlani, Mazari, Panjsheri, Kabuli, Herati, Kohistani, etc. Although in the past, some non-Pashto speaking tribes were identified as Tajik, for example, the Furmuli.