The Naga Club building in the heart of Kohima was vandalised by unknown people early on Saturday, police said.
The building housed the office of the Naga Students' Federation (NSF), the apex Naga students’ body in the Northeast, the office of the All Nagaland College Students' Union, the Kohima Press Club and other commercial establishments.
Kohima's Additional Superintendent of Police Relo T Aye said that the incident took place around 3 am, adding that an FIR has been lodged by the NSF, and an investigation is being carried out by a four-member Special Investigation Team (SIT) headed by him.
Various tools, including machetes and other sharp objects were seized from the spot.
Police suspected that the accused used earthmovers to damage the semi-concrete structures.
"Records related to Naga history were stored inside the building and are suspected to have been destroyed," NSF president Kegwayhun Tep told reporters here.
He hoped that the culprits will be brought to book.
The NSF issued an ultimatum to the government to nab the culprits by 6 pm on Sunday, failing which it will resort to action it deems befitting.
Chief Minister Neiphiu Rio strongly condemned the incident, tweeting, "Respect for private and public properties is fundamental in a civilized society."
He appealed to all citizens to maintain peace and harmony.
Nagaland Tourism Minister Temjen Imna Along expressed shock over the incident and said identities of the culprits should be revealed after their arrest.
Several tribal and youth bodies and civil society organisations condemned the act.
"Naga Club is Naga history, we cannot put a price on what our pioneers achieved and passed down to us," Angami Public Organisation said.
"NSF stood for the cause of the Nagas courageously. This ruthless attempt in destroying the fabric of the Nagas is most unfortunate," Naga Mothers' Association said.