Referenced In

The Travels of Marco Polo
by Marco Polo, da Pisa Rusticiano

"In the itinerary given it runs: … Ke-lin-fu (Kien-ning fu), Unken (Hu-kwan)…"

The Travels of Marco Polo
by Marco Polo, da Pisa Rusticiano

"in the last of those three days’ journey, when you have gone 15 miles you find a city called Unken, where there is an immense quantity of sugar made."