NANJING, Jan. 21 (Xinhua) -- The Memorial Hall for the Victims of the Nanjing Massacre will start to sort out the family trees of the victims and survivors of the massacre this year to preserve the evidence for history, sources with the memorial hall said Monday.

The Nanjing Massacre took place when Japanese troops captured the city on Dec. 13, 1937. Over six weeks, they killed 300,000 Chinese civilians and unarmed soldiers.

The survivors are living witnesses of the massacre. However, there are now less than 100 registered survivors, official data showed.

Zhang Jianjun, the curator of the memorial hall, said, "We hope the survivors and families of the victims could feel the warmth from the society and our memorial hall. We will brand the pains on our minds forever, but we should cherish our happiness today."

"Sorting out the family trees of the survivors and victims, including understanding the current situation of their next and third generations, we can know a group of people who could be the inheritors of historical memories," Zhang said.

An activity themed on welcoming the Spring Festival and praying for peace was held at the memorial hall on Sunday. Calligraphers sent their works and best regards to the survivors and families of the victims.

Ge Daorong, a survivor of the massacre, said, "The pain left by history will last forever, but we are glad that society has shown loving care for us."