TheTibetanastronomicalcalendricalcalculationhasalonghistory.TherearemanydocumentaryrecordsandTibetanpeoplehaverichexperiencesofit.TibetancalendricaldesignationofyearsasasummaryofTibetanpeople'sexperiencesintheirstrugglewiththenatureisanimportantpartofTibetanastronomyandcalendricalcalculation.Ittakestwelveyearsasasmallcycleand6oyearsasabigcycle.Abigcycleiscalled“rabjung”{rab-byung}inTibetan.Thefirstrabjungstartedin1027andthecurrentrabjungisthe17thrabjung.
