Complex sentence: Olaf Tryggvason travelled to Wendland to collect Thyri's dowry from King Bolesław and while there heard rumours of a planned ambush; but Sigvaldi arrived to tell him these rumours were false.
Split into simpler sentences: Olaf Tryggvason travelled to Wendland to collect Thyri's dowry from King Bolesław. While there he heard rumours of a planned ambush but Sigvaldi arrived to tell him that these rumours were false.