| Date | Event | From | To |
|---|
| 16 January 1964 | Erected | Diocese of Dibrugarh (Subansiri, Siang, and part of Lakhimpur)
Diocese of Shillong (Darrang, Nowgong, and parts of Goalpara and Kamrup)
| Diocese of Tezpur (erected)
|
| 26 June 1969 | Metropolitan Changed | | Diocese of Tezpur (from Calcutta)
|
| 20 January 1975 | Territory Lost | Diocese of Tezpur (Bhutan)
| Diocese of Darjeeling
|
| 30 March 1992 | Territory Lost | Archdiocese of Shillong-Gauhati
Diocese of Tezpur
Diocese of Tura
| Diocese of Guwahati (erected) (Kokhrajar, Dhubri, Goalpara, Barpetta, Nalbari, Kamrup, and Nagaon (except Rupahihat, Kaliabar, and Samugari))
|
| 10 July 1995 | Metropolitan Changed | | Diocese of Tezpur (from Shillong)
|
| 7 December 2005 | Territory Lost | Diocese of Tezpur (Tawang, West Kameng, East Kameng, Papum Pare, Upper Subasini, Lower Subasini, Kurung Kamey, West Siang, East Siang, and Upper Siang)
| Diocese of Itanagar (erected)
|