Sometimes you have to look out to see in.

WASHINGTON — Sometimes you have to look out to see in. An exhibition at the Smithsonian's Anacostia Community Museum about Africans in Mexico is not about race in America, or African American identity or what it means to be black in the United States. But by focusing on the particulars of African existence in Mexico, it reveals far more universal wisdom about race and identity than so much of the often rancorous "discussion" of the subject on this side of the border.

"The African Presence in Mexico: From Yanga to the Present" documents the arrival, disappearance and reappearance of African identity in Mexico over the past five centuries, using art from the colonial era, photographs and contemporary crafts, sculpture and imagery. Beginning in the 16th century, when enslaved Africans were brought on the first missions of discovery and conquest, it explores how the Spanish (long familiar with interracial existence given their proximity to Africa) articulated race into categories, including mulatto (half Spanish, half African), mestizo (half Spanish, half native) and 14 other permutations. The Catholic Church kept the records, slotting every newborn into a category that would determine its chances for an education, a career and even the most basic of rights.

After the war of independence from Spain from 1810 to 1821, these categories were suppressed as an unwanted vestige of Spanish colonial rule. The shorthand for ethnic identity recognized skin color, with fairer tones more privileged. Distinctions were still made between native and Spanish-descended identity, but African descent got lost in the mix.

The exhibit's most striking images show what was hiding in plain sight. As Mexico created a new melting-pot identity that assimilated yet denied blackness, artists documented the racial diversity that was officially disappearing. The three figures in a lithograph by Carlos Nebel, a German artist who traveled in Mexico from 1829 to 1834, all "read" black, at least to an outsider. Even two of the country's most prominent leaders during the struggle for independence, Jose Maria Morelos y Pavon and Vicente Guerrero, were of African descent.

And so the exhibition becomes a game: Find the African identity. This puts the viewer in the strange, and sometimes uncomfortable, position of looking for blackness in images of people who would not necessarily consider their African descent of much importance but who would, in this country, be labeled "black."

The exhibition seeks to document a suppression of identity that was, at first, perhaps progressive, but became over time a collective denial of the contributions of African-descended people. By the time you reach the Mexican Revolution (1910-1920), the popular conception of a new Mexican identity had marginalized the African presence.

This creation of a "brown" identity was an ambiguous project. Having African features was not the automatic ticket to poverty and discrimination that it was in most of the United States. But there was a cost: the loss of heritage, history and identity.

Even an idea as seemingly futuristic and idealistic as the "raza cosmica," or cosmic race, was a double-edged sword. This ideology of identity focused Mexican history on an epic encounter between the Old (and European) World, and the New World of indigenous Americans. Introduced by a prominent Mexican educator and politician in 1925, it offered the idea of a superior and emergent race, forged from the many identities that came together in places such as Mexico. It was a strange mix of colorblindness and racialist thinking that, after the dark chapters of the past century of world history, seems painfully ham-fisted.

The exhibition divides into roughly three chapters, beginning with the Spanish years, followed by the 19th- and 20th-century suppression of African identity, and closing with art that explores the recent emergence of a newly configured Afro-Mexican identity. After sorting through photographs made in Guanajuato, curator Cesareo Moreno of the National Museum of Mexican Art assembled a wall of faces, most obviously black. But even Moreno's uncle, who lives near where these standard portraits were made by a photography studio in the late 19th and early 20th centuries, said no black people were near the town.

When researching the exhibition, Moreno says, he was shocked to rediscover the blackness in a striking photograph made during the Mexican Revolution: of a dark-haired woman with full lips. Take her out of her Mexican clothes and put her in the segregated South and she would have been sent to the back of the bus.

But it wasn't until Moreno looked for it that he found her blackness: "Once you start seeing it, it is everywhere."

But would this young woman have defined herself as black? And if she didn't, who are we to "rediscover" it in her?

That leads to the powerful ambiguity of the exhibition's third chapter, devoted to artists who have focused on the newly emerging idea of an Afro-Mexican identity. The black photographer Tony Gleaton has worked extensively in Mexican regions with large African-descended populations, creating haunting images of dark-skinned people. But he wasn't perceived as "black" when he traveled in Mexico.

As a journal he kept in 1988 during his time in Mexico points out, he was also projecting his own ideas about race: "The photographs that I create are as much an effort to define my own life, with its heritage encompassing Africa and Europe, as an endeavor to throw open the discourse on the broader aspects of 'mestizaje,' the 'assimilation' of Asians, Africans, and Europeans with indigenous Americans."

There is an essential difference between finding something and forging something, and the exhibition's third chapter is about the latter.

If blackness seems to peer out of the silence of old images from earlier centuries, it is presented more boldly and sometimes stridently in art made since the slow reawakening of Afro-Mexican identity during the past few decades. The most provocative of the works is a painting commissioned for the exhibition from Arizona painter Alfred Quiroz. His 2005 "Kozmic Race" mobilizes just about every stereotype in the Mexican and American catalogue, from a hook-nosed and glowering conquistador to an African with chains on his arm and a bone through his nose, to a native Mexican, apparently holding human hearts as if fresh from some grisly Aztec ritual. It also references a 1938 lynching in Florida.

It is a strange and lurid assemblage, and an equal-opportunity offender. As art, it is intentionally cartoonish, and as a political statement, it eludes clarity by mobilizing intense and contradictory reactions with no sense of resolution or direction. It leaves one thinking what people south of the border have thought for centuries: Yanqui go home. Quiroz is Mexican American, but his painting feels very American, a projection of a particularly confrontational way of thinking about race and identity into a field, a country, a social entity, where this American habit may offer nothing particularly useful, and possibly much that is destructive.

Quiroz's painting makes one wish that "Afro-Mexican" identity could be studied and observed as if an objective fact. But there is no observing it without importing American and other ideas about race. And just as you're about to dismiss Quiroz's painting, you realize art has always been used to forge ethnic and racial identities. His painting is a part of a centuries-old project.

But is it a good project? Does it need to continue? Is a forgotten or suppressed identity best left dormant? Or is there a way to awaken difference without division, identity without animosity? Like all good exhibitions, "The African Presence in Mexico" raises more questions than it answers. But it goes beyond the merely good by raising provocative and painful questions in a forthright way alien to all too many exhibitions about race today.