Dia (Jà) is a small town and seat of the commune of Diaka in the Cercle of Ténenkou in the Mopti Region of southern-central Mali. It is situated at the western edge of the Inland Delta floodplain, and is watered by the Diaka, one of the Niger River's major distributaries and the only permanent watercourse in the region.

Tigemaxo and also some Fulfulde are spoken in Dia.

The three-settlement mound complex of Dia, located at the western edge of the Inland Niger Delta of Mali, is known for rich oral and written resources, and predates the much better-known cities of nearby Djenne and Timbuktu. According to Levtzion, the Diakhanke "remember Dia in Massina as the town of their ancestor, Suware, a great marabout, and a saint." This vast site thus offers the possibility of studying the beginning of urbanization in this part of Africa and the structure of an early West African city.

Favorable climate and water supply have favored human settlement for centuries, and the history of the region is linked to that of former western Sudan with the successive empires of Ghana, Mali and Songhay. The water system provided a favorable route for trade between the southern and northern Sahara, making Dia as one of the key trade sites in the region.

Since 1980, efforts have been made to make an inventory of the archaeological sites in the Inland Niger Delta to better understand their size and preservation. One of them was the large-scale excavations initiated by Rijksmuseum voor Volkenkunde at Leiden, within the framework of a long-term Malian-Dutch cultural heritage program. The initial prospection was carried out in 1998 in the Inland Delta, and the vicinity of Dia was chosen as the principal research zone for the project.

The settlement complex at Dia consists of an agglomeration of three separate large archaeological sites: Dia-Shoma, Dia, and Dia-Mara. With an area of 49ha, Dia-Shoma is the largest and oldest, dating back to the 9th century BCE. It is the only one of the three that was permanently abandoned. Dia, measuring 23ha, is still occupied today, while Dia-Mara, measuring 28ha, has been largely abandoned but is still partly in use as a burial site. These sites dates to the sixth century BCE and the height of settlement at this complex reached around the 10th century CE . Meanwhile, occupation does not begin until the sixth-century CE at the neighboring mound of Dia-Mara.

The only attempt at a detailed geomorphological study of the Dia was the one by Haskell et al. (1988), which resulted from an explorative field season consisting of text excavations at Shoma and Mara, and the survey of Dia's hinterland. The survey discovered Dia and its hinterland which are extensively cultivated with rice during the annual Niger flood. Also, some 37 further sites have been identified by Haskell et al., which is in a 5 km radius around the principal settlement mounds.

The spindle whorls, which is an object used to spin both wool and cotton threads, have been identified in Shoma and Mara in a variety of contexts. A wide variety of shapes and sizes are observed among them, and most of them are elaborately decorated with incised lines, triangles, circles, and dots. They are common black terracotta types found in many regions of West Africa.