If we take Samarqand in the year 725, the "official spoken" language of the city was still Soghdian, witness the Soghdian letters found in 1934 in Mt Mug east of Panjikant. The "official written" language was Arabic, since the Arabs ruled the city. The "religious" language was also Arabic for Muslims, and Avestan with Pahlavi for Zoroastrians. At home Soghdian dialects were spoken. A hundred years later Persian had replaced Soghdian as the "official spoken" language, whereas Arabic remained as the "official written" language though soon (probably under Nasr b. Ahmad or Isma'il b. Ahmad) to be changed to Persian. The "religious" language was now almost exclusively Arabic since most of the population had become Muslim. At home Soghdian dialects were still spoken as well as more and more Persian. As noted above, we do not know where the first writing of Persian in the Arabic alphabet occurred, but the Samanid bureaucracy from the time of Isma'il was based on both Arabic and the new Persian form of writing. The Samanids were the first to "Persianize" the bureaucracy as copied from Baghdad, which in turn had borrowed from Ctesiphon, the capital of the defunct Sasanians. It is probable that the Sasanian bureaucracy had been strongly under the influence of the Zoroastrian clergy in pre-Islamic Iran. References to mobads in the Middle Persian and Arabic literatures, as well as the enormous number of Sasanian seals with the names of priests on them, indicate the importance of the Sasanian clergy. The class of scribes, however, did exist and was separate from the clergy, which is why it survived to serve new Arab Muslim masters, whereas the priests, of course, had to retire from any positions of influence in the government after the coming of Islam. The scribes, on the other hand, were of vital importance for the bedouin conquerors, for only the scribes could keep the accounts and help the Arabs rule their new conquests in the east. Consequently, after the Arab expansion the role of the scribes in Iran increased in importance compared to Sasanian times, where they had performed little more than the bookkeeping for the secular chiefs and for religious officials such as judges and lawyers.