 They were always welcomed by the regional authorities  since the latter were interested in increasing the revenue and the exploitation of the mineral-rich subsurface was quite profitable.
<fluency>  They were always welcomed by the regional authorities  since the latter were interested in increasing the revenue and the exploitation of the mineral-rich subsurface was quite profitable.
 They were always welcomed by the regional authorities , since the latter were interested in increasing the revenue and the exploitation of the mineral-rich subsurface was quite profitable.