<prompt> Translate the following text to SwahiliDuring the fifth century a number of Celtic tribes came together to form the Kingdom of Rheged, which is said to have stretched north over what is now the Scottish border and south as far as the River Mersey.  <response>: Katika karne ya tano, makabila kadhaa ya Waselti yaliungana na kuunda Ufalme wa Rheged, ambao unasemekana kwamba ulipanuka kaskazini hadi mpaka wa sasa wa Scotland na kusini hadi Mto Mersey. 