As religious sciences in the Islamic other, the developing science of Usul Fiqh to remain grounded in the Quran and the Sunna. Usul Fiqh been around since the time of the Prophet and Companions. The main problem that is part usul fiqh, such as ijtihad, qiyas, nasakh, and takhsis existing at the time of the Prophet and Companions.
At the time of the Prophet Islamic legal sources only two, namely the Qur'an and Sunnah. If a case appears, the Prophet waited for a clear revelation of the case law. If not down the revelation of Allah menetapkam case law through his saying that we are familiar with the Hadith or Sunna.
When a problem can not be explained or resolved by the Quran and Sunna, then it can be done through the following indicators, through ijtihad, qiyas, etc.. Indicators strung in usul fiqh.
Usul Fiqh is the rules used in an attempt to obtain syara laws' of the acts of his theses are detailed. And efforts to obtain such legal, among others with ijtihad.
Since the time of the Prophet, companions, Tabi'in and afterward, the Islamic legal thought developed. However, the style or method of thinking in terbukukan not be made systematic. In other words, not shaped as a separate discipline.