Some 10,000 adherents remain in the Central Asian regions that were once considered the traditional stronghold of Zoroastrianism, i.e., Bactria (see also Balkh), which is in Northern Afghanistan; Sogdiana; Margiana; and other areas close to Zoroaster's homeland. In Iran, emigration, out-marriage and low birth rates are likewise leading to a decline in the Zoroastrian population. Zoroastrian groups in Iran say their number is approximately 60,000. According to the Iranian census data from 2011 the number of Zoroastrians in Iran was 25,271.