The Shi'ah Muslim Fiqh progressed in this era to a considerable degree due to a favorable political environment. Thousands of scholars attended the study circles of Imam Muhammad al-Baqir (a.s) and Imam Ja'far al-Sadiq (a.s) in this era and then disseminated the knowledge throughout the Muslim world. Accordingly, the Shi'ah Muslim jurisprudence received a stronger foundation.

In this era very prominent figures in jurisprudence emerged. Aban Ibn Taghlab, Muhammad Ibn Muslim, Zurarah Ibn A'yan, Jabir Ibn Yazid al-Ja'afi, Mu'awiyyah Ibn Ammar Sabati were of those Scholars. Imam al-Sadiq (a.s) referring to these personalities stated, "Had some of these scholars not existed, the sign of prophethood would have vanished 47. It was in this era that thousands of works on Hadith were compiled 48.

3. The third stage

The third stage, through which the Shi'ah Muslim Fiqh passed, was known as the Radawi era. This era testifies to the existence of divergent and chaotic views concerning hadith. Hadith was and still is the main source of Shi'ah Muslim Fiqh. Imam Rida (a.s) examined and edited the books on hadith and thereby made a significant change 49. Hasan Ibn Ali Ibn Washsha, one of the companions of Imam Rida (a.s), has said that once he saw 900 Shaykh (scholars) in the Kufa mosque each saying, "I heard Ja' far Ibn Muhammad say so and so 50"

4. The next stage

The next stage was known as the 'askarayn era. The rulers in this era leveled the repressive measures against Imam al-Hadi (a.) and Imam al-Hasan al-'askari (a.s), to the extent that they lived as captives of the tyrant rulers. The Shi'ah Muslim Fiqh had a setback in this era. The Shi'ahs were in a state of Taqqiyyah (secretive of identity). Despite all these difficulties, books on Shi'ah Muslim hadith reached to number 6,600 51.

5. Following the 'askarayn

Following the 'askarayn was the era of Nuwwab (representatives). Four people were appointed during 260-329 A.H.). This era is better known as the era of minor occultation of Imam al-Mahdi (a.s). Imam Mahdi (a.s) dealt with the matters of Fiqh through four appointees or representatives one after the other. In the suffocating and repressive atmosphere at that time, Shi'ah Muslim Fiqh was discussed and taught in hidden schools.

6. From the beginning of major occultation

From the beginning of major occultation (329 A.H.) to the era of Shaykh al-Tusi (460 A.H.) may also be considered an era of the some activities in the school of Fiqh. More activities in the school of Shi'ah Muslim Fiqh took place in this era and the discipline of Ijtihad developed further. In this era the 400 principal documents that contained the texts of Fiqh were compiled in the form of the four principal works on Fiqh. During a 20 years of study and research work, Kulayni collected 16,190 hadith in his al-Kafi. These Ahadith are more than the Ahadith in Sihhah al-Sittah.

Muhammad Ali Ibn Babwiyah (381 A.H.) collected 5,963 hadith in his Man La Yahzarhu al-Faqih. These were a source for his opinions in Fiqh. Al-Shaykh al-Tusi (460 A.H.) collected 13,590 hadith in his Tahdhib and 5,511 hadith in his Istibsar.

The great scholars of Fiqh like Shaykh-e Mufid, Sayyid Murtaza, Sayyid Radi, and Shaykh al-Taif'ah lived in that era. These eminent scholars formulated the proper Ijtihad, and established the methodology and logic of Fiqh which is called 'usul al-Fiqh. The following scholarly works were produced in that era:

1. al-Tadhkirah bi 'usul al-Fiqh by al-Shaykh al-Mufid (413 A.H.).

2. al-Dhari'ah ila 'usul al-Shari'ah by Sayyid Murtaza (436 A.H.).

3. 'Idat al-'Usul by Shaykh al-Tusi (460 A.H.).

4. al-Mabsut fi Fiqh al-Imamiyyah by Shaykh al-Tusi.

5. al-Khilaf by Shaykh al-Tusi.

7. The next era

The next era with some effect on Fiqh was the Fitrat, inactive period, (from al-Shaykh al-Tusi up to the time of Ibn Idris). The dominant figure of this era is al-Shaykh al-Tusi. Other scholars of Fiqh referred to him in the matters of Fiqh. This era is known as the era of Taqlid (following) and lasted for 10 decades. It was Ibn Idris of Hilla, Iraq who ended this state and thereupon revived Ijtihad (reasoning and research). One of his main works is Al-Sara'ir.

8. The era of some progress

The era of some progress in Fiqh emerged on the scene (from Ibn-Idris to 'Allamah Hilli (726 A.H.)). In this era the great scholars like Sa'id abul Makarim Ibn Zuhrah (585 A.H.), Ja'far Ibn Hasan al-Hilli, better known as Muhaqqiq (677 A.H.), and Hasan Ibn Hasan Mutahhar al-Hilli, better known as 'Allamah al-Hilli (726 A.H.) were the authorities in Fiqh and 'usul al-Fiqh.

9. The next era

The next era is known as the second Fitrat, inactive period. This era commenced with 'Allamah al-Hilli and extended up to the era of 'Allamah Wahid Bihbahani (1208 A.H.). The Akhbari (disbelief in 'usul al-Fiqh and following the letters of the text of Fiqh) influence in this era, impeded Itihad to certain degrees. The most non-controversial work in this era is done by al-Shaykh Yusuf al-Bahrani (1186 A.H.) entitled al-Hada'iq al-Nazirah.

10. The era of more progress

The era of more progress in Ijtihad followed. After the severe criticism of 'Allamah Wahid Bihbahani of the Akhbari trend of thought, he revived Ijtihad on the basis of principles the Ahl al-Bayt (a.s) had set forth. This progress has continued to the present time.

Following are prominent works of this era:

1. Jawahir al-Kalam by Shaykh Muhammad Hasan Najafi (1262 A.H.)

2. Makasib by Shaykh Ansari (1281 A.H.)

3. Misbah al-Faqih by 'Allamah Haj Agha Rida Hamadani (1322 A.H.).