OSAKA -- Shards of a large jar dating from around the mid-fifth century have been found at Japan's largest mounded tomb in Sakai, Osaka Prefecture, which the Imperial Household Agency designates as the mausoleum of Emperor Nintoku, Kyodo News reported Saturday.

Intact, the jar would have measured 62 cm tall and about 62 cm in diameter. Fragments for about half the jar have been found. The mouth of the jar indicates it was made around A.D. 450 at a nearby ancient official factory called Suemura, archaeologists said.

The mid-fifth century is believed to be the time when the mounded tomb was completed and when the funeral was held, the archaeologists said.

"Sue" earthenware became an established form of unglazed pottery and began spreading nationwide around 450, they said.

It can provide important clues to determining archaeological periods and the shards just found in Sakai suggest that the keyhole-shaped tomb was built closer to the year in which Emperor Nintoku is estimated to have died based on the "Record of Ancient Matters."

The year in which Emperor Nintoku died has remained a mystery to modern historians. It is calculated at 427 when based on the "Record of Ancient Matters," and 399 when the "Chronicles of Japan" is used.

There have been many theories that Emperor Nintoku died in the late fifth century and that the person buried in the tomb was not Emperor Nintoku.

The location where the sue ware fragments were found suggests the jar was used for funeral purposes, the archaeologists said.

The tumulus, which is protected and preserved by the Imperial Household Agency, has never been fully excavated.

The period in which the tomb was built had been estimated by using such articles as clay images found during repair work and from records of burial goods found during the Meiji period from 1868 to 1912.