A researcher specializing in the early history of the Ottoman Empire says he has identified what he believes is a steel helmet belonging to Osman I, the founder of the empire, in the inventory of the Metropolitan Museum of Art in New York.

Hakan Yılmaz, a modern history specialist and researcher, said the discovery follows what he described as earlier findings of an early Ottoman coin in Qatar and an original genealogical record in Paris.

Speaking in an interview with journalist İbrahim Öge, Yılmaz said the helmet bears a seal associated with the Kayı tribe and a mark he attributes to Osman I. He argued that the artifact settles long-running debates over the Ottoman founder’s ethnic origins and his political status as an independent ruler.

"This helmet not only confirms that Osman Bey was a ‘Sultan’ and founded an independent state,” Yılmaz said, "it also puts an end to long-debated questions about his ethnic origin and tribal status.”

Yılmaz also said the helmet includes silver-inlaid Arabic inscriptions in which Osman I is described using titles he translated as "Sultān al-A‘zam” (Great Sultan) and "Khān al-Mu‘azzam” (Exalted Khan). He added that a medallion on the reverse side contains the inscription "Nāṣir al-Dīn ‘Uthmān Sultan,” which he said contradicts academic arguments that Osman I was not an independent sultan.

He further described a historical practice in which archival documents and military artifacts were stored in various Ottoman-era facilities in Istanbul after the conquest of the city, including the Hagia Sophia complex and underground storage areas used by the Imperial Arsenal at Aya Irini. According to Yılmaz, items were later entered into private collections across Europe and eventually into museums.

Yılmaz said the helmet he attributes to Osman I was later part of the collection of George Cameron Stone and was donated to the Metropolitan Museum of Art in 1935 after Stone’s death, in accordance with his will.

He also cited what he described as errors in a study conducted 11 years ago by specialist David G. Alexander, saying the museum catalog accurately described the helmet’s physical features but omitted portions of the inscription, including references to the name "Osman.”

Yılmaz said he has also identified additional helmets in museum and auction collections that he believes may be linked to early Ottoman rulers, including one attributed to Murad I at the Metropolitan Museum of Art and another he associates with Orhan I based on stylistic and inscriptional similarities. He said analysis of these items is ongoing.

In addition, he called for Turkish authorities to take steps to repatriate what he described as early Ottoman artifacts, including the Qatar coin, the Paris genealogical record and the helmet in New York.

"These should be displayed to the public,” Yılmaz said. "They could be exhibited in Topkapı Palace alongside the sword attributed to the Prophet David, or in the Military Museum together with the helmet of Orhan. Alternatively, a new museum could be established in Bursa. The Turkish public should be able to see and experience this historical heritage directly.”