Standing near the grave of a slave owner who once held his great-grandfather as property, the Rev. Al Sharpton on Monday encouraged all African-Americans to explore their history despite "the ugly things it might reveal."

"As painful as it is, it's good that it comes out so we can deal with it," said Sharpton, who learned a week ago that he descends from slaves owned by ancestors of the late Sen. Strom Thurmond, a former segregationist.

Sharpton's trip from New York to this rural town where Thurmond was born included a visit to a cemetery where slaves are buried in graves marked only by small stones.

Professional genealogists working for Ancestry.com found that Sharpton's great-grandfather Coleman Sharpton was a slave owned by Julia Thurmond, whose grandfather was Strom Thurmond's great-great-grandfather. Coleman Sharpton was later freed.

The owner of a plantation-style home here, Phillip White, said Sharpton's great-grandfather would have worked on the 10 acres of land and he believes some of the civil rights activist's relatives may be buried in the nearby cemetery.

White gave Sharpton a horseshoe he found in the slave quarters on his property.

Sharpton's trip to trace his roots back to this rural town near the Georgia border comes after Thurmond's biracial daughter said he "overreacted" when he learned about the link to the Thurmond family. Sharpton called the revelation "the most shocking thing in my life."

Last week, Essie Mae Washington-Williams, 81, defended Thurmond and spoke about all the positive things he did for South Carolinians — both black and white.

The longtime South Carolina senator was once considered an icon of racial segregation. During his 1948 bid for president, he promised to preserve segregation and filibustered for more than 24 hours against a civil rights bill in 1957. He softened his segregation stance later in his life.