Referenced In

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

"“Singpho,” says Colonel Hannay, … all of this race who have settled in Hookong or Assam are thus designated"

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

"Mr. Blyth tells me a stray one has been seen in Assam or its borders."