Complex sentence: Rodoviária Sul do Tejo became, in late 90's, TST-Transportes Sul do Tejo, since 2002 is owned by Arriva group, which entered in the portuguese market in 2000 owning some medium sized operators in the northwest of Portugal.
Split into simpler sentences: Rodoviária Sul do Tejo became, in late 90's, TST-Transportes Sul do Tejo. Since 2002 is owned by Arriva group, which entered in the portuguese market in 2000 owning some medium sized operators in the northwest of Portugal.