Research of the monuments complex of the Great Hillfort territory, including the Tiahyn fortress, was started by the South Medieval Expedition of the Institute of Archeology of the National Academy of Sciences of Ukraine in 2016 and continued annually until 2021. During this time, the area of the Great Hillfort island, surrounded by the Tiahynka River, was surveyed. There is a complex of objects from various chronological periods: from the Bronze Age to the late Middle Ages, and early Modern times. One of the largest cities of Ulus of Jochi of the Mongol Empire was located here, on the Great Hillfort, from the end of the 13th century until 1360–1370s. Later, from the end of the 14th to the early 15th century, during the Grand Duke of Lithuania Vytautas times, a castle-type stone fortress was built.
The history of the settlement archaeological research is connected with the famous scientist, and founder of the Kherson Historical Museum, V.I. Hoshkevych, who conducted comprehensive surveys and excavations on the territory of the Great Hillfort in 1914. The main efforts were aimed at excavating the Tiahyn fortress, which is located in the southwestern part of the settlement. Hoshkevych presented the island’s topographical plan, made an attempt to draw up a plan of the Tiahyn fortress, excavated its eastern part, discovered the remains of a rampart and moat, triangular fortifications, and a system of buttresses, investigated the remains of a dungeon built of local limestone. He considered the fortress was a Lithuanian castle and customs house, and identified it with one of the fortification points, built by the Grand Duke of Lithuania Vytautas in the early 15th century. At a distance of more than 1 km to the north-east of the fortress, he excavated 12 burial mounds where the remains of 15 men were found. The burial ground is synchronous with the materials of the fortress. Artifacts from Hoshkevych excavations became part of the Kherson Regional Museum of Local History collection.
Further, various archaeological works on the Great Hillfort and the Tiahyn fortress, in particular, were carried out by S.O. Sekretnyi (1936), M.I. Olenkovska (Abikulova) and M.P. Olenkovskyi (1977), V.B. Pyvorovych (2000s), S.B. Bakhmatov (1992–1993), V.E. Illinskyi (2009–2010), D. Kobalia (2018).
The research of the South Medieval Expedition of the Institute of National Academy of Sciences of Ukraine (led by Dr. S.O. Biliaieva) lasted from 2016 to 2021. It confirmed the conclusions of V.I. Hoshkevych on the chronology and fortress belonging to the Grand Duchy of Lithuania, Rus, and Žemaitija times of Duke Vytautas. However, thanks to the research led by O.V. Chubenko and M.M. Iievliev, it was concluded that only the eastern part of the fortress was discovered by V.I. Goshkevich. With the help of a quadrocopter, its western part was defined, and a complete plan of the fortress was made. It belonged to the triangular Constantinople type of planning. The dimensions of the fortress were determined. O.V. Manihda and O.V. Hrabovska’s work resulted in a topographical plan of the fortress and a relief model of the site. Excavations of the Tiahyn fortress revealed it was a stone structure of the castle fortification, typical for the all-European type of fortresses of the 14th–16th centuries. Its area is 0.73 hectares. The thickness of the fortress walls is 0.8–1.2 m. The remains of a multi-tiered watch tower were discovered in the south-eastern corner. Its floor was supported by strong timber pillars. A Genoese-type bombard with stone cores was waiting for the enemies. During the excavations of the tower first floor timber platform, fragments of the bombard barrel were found, and a limestone cannonball.
The complex of artifacts that present the bright syncretic culture of Southern Ukraine is extremely interesting. There were elements of the culture of the West and the East: Lithuania, Poland, Italian Genoa, Crimean Tatars, and the Ottoman Empire. The representatives of the Grand Duchy of Lithuania left their heraldic sign here, as evidenced by carvings on a limestone slab. It might have decorated the front entrance to a large stone house in the inner courtyard of the fortress, not far from the watchtower. The customs office with Lithuanian merchants or customs officers is evidenced by cross-shaped bronze and iron plates for leather bags. Analogs for those are known from the Lithuanian sites. King Władysław Warneńczyk from Kraków coins revealed trade relations with Poland already in the first half of the 15th century. The connection with Genoese is marked by artillery weapons and Tatar coins with the countermark of the Crimean Genoese Kafa. The lively ties with the Crimea, where the tradition of sgraffito ceramics of Byzantium continued and new features of the Crimean Tatar and early Ottoman Crimea ceramics developed, are evidenced by numerous samples of tableware. These include dinnerware decorated with gilding, colorful glazes, and exquisite decor.
The next pages of the history of Tiahyn, the struggle of Lithuania and the Crimean Khanate for the heritage of the Northern Black Sea region, and perhaps the first pages of the history of the Ukrainian Cossack hetmans, were revealed in an extremely rare find – the end of 15th-century iron mace. The subsequent establishment and strengthening of the Crimean Khanate and its trade relations is evidenced by numerous finds of mainly silver coins with the stamp of Mengli Giray.