Three out of Four Khalifa were martyred / killed by Hypocrites. Ummah is widely divided and still not ready to research / investigation on what happened to this Ummah and how it got deviated and are still being wiped out one after another for centuries. There is no doubt on the Quraan and it is fully protected by Allah, BUT We MUST have to investigate on everything from the beginning of the birth of Prophet Muhammad (Peace-Be-Upon-Him). Here I would like to highlight on Origin of Hadeeth Collectors (Muhaddith). Not a single Muhaddith were born or ever lived in Makkah or Madina of Hijaz (present day Saudi Arabia). Hypocrites are like Cancers among Muslims and they MUST need to be exposed. We MUST need to verify all Hadeeth and accept those Hadeeth which are truly according to the Quraan.

1. AHMAD (Ibn Hanbal):

Ahmad bin Muhammad bin Hanbal Abu Abd Allah al-Shaybani (164–241 AH), was a Persian Islamic scholar.
Born:    Rabi-ul-I, 164 AH/November, 780 in Baghdad, Iraq.
Died:    12 Rabi-ul-I, 241 AH/2 August, 855 in Baghdad, Iraq.

2. AL-BUKHARI, Muhammad bin Ismail:

Abu Abd Allsh Muḥammad ibn Ismsil ibn Ibrahim ibn al-Mughirah ibn Bardizbah al-Jufi al-Bukhari (194 A.H.), was a Persian Islamic scholar.
Born:    19 July 810 C.E., 13th Shawwal 194 A.H., Bukhara, Transoxiana (in present-day Uzbekistan)
Died:    1 September 870 (aged 60) C.E., 1 Shawwal 256 A.H., Khartank, near Samarqand.

3. MUSLIM bin Hajjaj:

Abu al-Husayn Asakir ad-Din Muslim ibn al-Hajjaj ibn Muslim ibn Ward ibn Kawshadh al-Qushayri an-Naysaburi was born in 204 A.H. in the city of Nishapur near the city of Mashhad in present Iran, was a Persian Islamic scholar.
Born:    after 815, 204 A.H., Nishapur, Khorasan, (in present-day Iran).
Died:    May 875, Resting place     Nasarabad, (a suburb of Nishapur)

4. ABU DAUD, Sulaiman bin Al-Ashath:

Abu Dawud Sulayman ibn al-Ashath al-Azdi as-Sijistani (202 A.H.), was a Persian Islamic scholar.
Born:    817–18 CE, 202 A.H., Sigistan, a famous city in Khorasan, (in present-day Iran).
Died:    889 CE, Basra

5. AT-TIRMIDHEE, Abu Iesa Muhammad bin Iesa:

Abu Isa Muhammad ibn Isa as-Sulami ad-Darir al-Bughi at-Tirmidhi was born in 209 A.H. in a town called Tirmiz in Uzbekistan near the northern border of Afghanistan, was a PersianIslamic scholar.
Born:    824/ 209 A.H., Termez, now Surxondaryo Region, Uzbekistan.
Died:    9 October 892/ 13 Rajab 279 A.H. (aged 68), Termez, now Surxondaryo Region, Uzbekistan.

6. AN-NASAI, Abu Abdur-Rahman Ahmad bin Shuaib:

Abu Abdur-Rahman, Ahmad bin Ali bin Shuiaib bin Ali Al-Hafiz was born in 215 A.H. in Nisa, a city in Khurasan, was a Persian Islamic scholar.
Born:    214 A.H. (c. 829 CE), Nasa, present-day Turkmenistan.
Died:    303 A.H. (915 CE).

7. IBN MAJAH, Muhammad bin Yazid:

Abu Abdillah Muhammad ibn Yazid Ibn Majah al-Rabi al-Qazwini (207 A.H.) commonly known as Ibn Majah, was a Persian Islamic scholar.
Born:    824 CE, 207A.H. Qazvin.
Died:    887 (or 889) CE.

Map of Origin of Hadeeth Collectors:

http://www.global-right-path.com/Ummah-Reformer/MR_Hadeeth_Collectors_Origin_Map.jpg