Inside his Marscloud Art Gallery in Manassas, Virginia, Kuang Lin doesn't begin by talking about brushwork, composition, or color. Instead, he talks like an investigator, pointing to what he considers proof.

On one painting of a fort, two Chinese characters, haizhu, sit high like a nameplate, anchoring the scene to a location that no longer exists.

On another, the evidence isn't on the front but on the back — a handwritten note describing a battle, a death at a porthole, and a line of pidgin English that still echoes — "Sick man yami guns?"

This habit of interpreting images as evidence helps explain why Kuang is an unusual figure in the world of Guangdong "China trade" paintings — works produced in southern China from the late 18th through the 19th centuries for export to Europe and America.

Trained as an engineer and long employed in computing, Kuang is a self-taught collector and researcher whose decades of collecting Chinese art in the United States led him ultimately to a trove of Qing Dynasty (1644-1911) trade paintings.

The pipeline that carried these works overseas was already forming by the late 1700s. Canton, or Guangzhou, the capital of Guangdong province, had been the key source of supply.

Foreign merchants, restricted to a small area outside the city walls, were assigned hong (trading houses), and Western demand — what Carl L. Crossman described as an "insatiable" interest in "things Oriental" in his 1972 book, The China Trade: Export Paintings, Furniture, Silver and Other Objects — helped drive a flood of made-for-export goods, including paintings such as portraits and port scenes, that found eager buyers in Europe and the US.

Today, Kuang's gallery holds at least 30 such Qing-era oil paintings — on canvas, wood panels and ivory — alongside more than 700 watercolors on paper, pith and mulberry leaves, grouped by the gallery as "Qing Dynasty Guangdong Historical Paintings".

"In an era before photography, China trade paintings of forts and others were the sole visual chroniclers of a world now lost to time," Kuang says.