Original: Since King Christian X was also the King of Iceland at the time, as a tribute to the people of Iceland, the Princess was given an Icelandic name, Þórhildur (spelled with the Icelandic thorn character, simplified as "th").
Simplified: As King Christian X of Denmark was also the King of Iceland at the time of her birth, the Princess was given an Icelandic name, Þórhildur (spelled with the Icelandic thorn character, simplified as "th").