Dokdo is a group of small islets in the East Sea.
There are a lot of reports saying that Dokdo is Korea's territory, but Japan keep insisting that Dokdo is their territory and uses the name Takeshima.
The old name of Dokdo was Usando and it was recorded in <Sejongsillok> for the first time in the name of Usando.
In geography book called <Paldochongdo> which was made in 16th century, Dokdo was painted.
Also in 1900, Gojong made it clear that Dokdo is Korea's territory.
However after the treaty between Korea and Japan, Japan claimed Dokdo should be included in shimane prefecture.
So, they started to call Dokdo as Takeshima and insisted that Dokdo belonged to them.
But this is explicitly illegal under the international law.
Therefore, the word Takeshima shouldn't be used.