Richmond, Virginia (CNN) -- A historical society in Virginia, where slavery began in the American colonies in 1619, has discovered the identities of 3,200 slaves from unpublished private documents, providing new information for today's descendants in a first-of-its-kind online database, society officials say.

Many of the slaves had been forgotten to the world until the Virginia Historical Society received a $100,000 grant to pore over some of its 8 million unpublished manuscripts -- letters, diaries, ledgers, books and farm documents from Virginians dating to the 1600s -- and began discovering the long-lost identities of the slaves, said society president and CEO Paul Levengood.

The private, nonprofit historical society, the fourth-oldest in the nation, is assembling a growing roster of slaves' names and other information, such as the slaves' occupations, locations and plantation owners' names, said Levengood.

The free, public website also provides a high-resolution copy of the antique documents that identify the slave....