Dughore is also a name for an area in southwest Kolombangara, Kolei is the general bilateral address term specific to Nduke.
Oral history in Dughore recounts that the northwest, northeast and southeast of Kolombangara had their own languages, which became extinct when the people of those areas were annihilated in warfare that probably occurred in the early 19th century.
[2] Inter-island exchange with neighbouring island language areas of Vella Lavella, Simbo and Roviana was strong in the latter 19th century, possibly leading to some language borrowing, although marriage remained largely endogamous at that time.
In the early twentieth century, colonial rule instituted Roviana as a lingua franca, and the Seventh-day Adventist church, which was widely adopted on Kolombangara, used Bible materials written in Marovo.
Roviana, although it ceased to be a regional lingua franca in the 1960s, is still widely understood by Duke speakers.
As a result, Pijin is a widely used household language on Kolombangara, which in some families has almost fully replaced Duke.
Recent lexical work on Nduke has used a composite of these two orthographies to avoid ambiguity.