the diocese of hamar was established and separated from oslo in 1152, but it was again merged with oslo in 1541 (together with the northern part of østerdalen from diocese of nidaros). the regions of hallingdal and valdres were transferred from diocese of stavanger to oslo in 1631. (but oslo had to give the upper part of telemark to stavanger in return.) the parishes of idre and särna were lost to sweden in 1644, and the province of bohuslän was lost in 1658. hamar (with hedmark and oppland) was again separated from oslo in 1864. the rest of telemark was transferred to "diocese of kristiansand" (see diocese of agder og telemark) the same year. the diocese of tunsberg (with vestfold and buskerud) was established and separated from oslo in 1948. the diocese of borg (with akershus and østfold) was established and separated from oslo in 1969.