Ivanov was the first scholar to study the printed books and manuscripts written in the as yet undeciphered Tangut script that had been found in the abandoned city of Khara-Khoto in Inner Mongolia by Pyotr Kozlov in 1908–1909. In autumn 1909 as many as 24,000 volumes of books and manuscripts in Chinese, Tangut and other languages, together with numerous archaeological artefacts, had been sent to the Russian Geographical Society in Saint Petersburg by Kozlov. The books and manuscripts were subsequently moved to the Asiatic Museum of the Academy of Sciences (now the Institute of Oriental Manuscripts of the Russian Academy of Sciences). Together with V. L. Kotvich (Władysław Kotwicz), a Polish scholar of Mongolian and Manchu, Ivanov worked on the identification and preservation of the books and manuscripts from Khara-Khoto. Among these books Ivanov discovered a bilingual Chinese-Tangut glossary called the Pearl in the Palm () which he realised was the key to deciphering the Tangut language. He later discovered three monolingual Tangut dictionaries and glossaries: Homophones (); Sea of Characters (); and Mixed Characters (). Based on the Pearl in the Palm and the other dictionaries, Ivanov was able to compile a dictionary of about 3,000 Tangut characters. The dictionary was completed in 1918, and deposited at the Asiatic Museum, where it remained until 1922, when Ivanov took it back. Due to the unstable political situation at the time, the dictionary was never published, and was not even known to Ivanov's most famous student, Nikolai Aleksandrovich Nevsky, whose posthumous work, Tangut Philology (1960), laid the bedrock for modern Tangut scholarship. Ivanov's dictionary, which was at his home at the time of his arrest and execution in 1937, has never been seen since.
