Purnawarman ruled the Tarumanagara kingdom in western Java during the mid-fifth century. The Tugu inscription, the longest of his surviving edicts, was carved during the 22nd year of his reign to commemorate two hydraulic projects. The first, ordered by an earlier ruler referred to as Rajadirajaguru, channeled the Chandrabhaga river toward the sea past the royal palace. The second, Purnawarman's own project, involved digging a canal for the Gomati river through the grounds of his grandfather's estate. The inscription describes the king with the Sanskrit epithet for strong-armed, a ruler whose power was measured not in conquests but in the ability to redirect water. The canal stretched 6,122 bow-lengths, and the work took just 21 days from its auspicious start date on the eighth day of the dark fortnight of the Phalguna month.

The inscription was written in Pallava script, the writing system that spread from southern India across Southeast Asia during the first millennium. Its text is arranged as Sanskrit sloka verse in the Anustubh meter, the same poetic form used in the Mahabharata and Ramayana. Five lines of text wrap around the stone's curved surface, with a trident-topped staff motif marking where sentences begin and end. Paleographic analysis dates the script to the mid-fifth century, though like all Tarumanagara inscriptions, the stone carries no explicit date. Scholars have noted that the handwriting closely resembles the Cidanghyang inscription, another Purnawarman edict found in Banten province, suggesting a single court scribe may have been responsible for both. The language choices reveal a kingdom deeply connected to Indian cultural traditions while rooted firmly in the Javanese landscape.

For centuries the inscription sat in Batutumbuh hamlet in Tugu village, Koja, on the northern outskirts of what would become Jakarta. It was one of those objects that locals knew about but that the wider world had not cataloged. In 1911, a Dutch colonial official named P. de Roo de la Faille arranged for the stone to be transported to the Museum of the Batavian Society of Arts and Sciences, the institution now known as the National Museum of Indonesia. It was given inventory number D.124. European scholars had been studying Purnawarman's inscriptions since the early 1900s, and the Tugu stone attracted particular attention because of its unusual subject matter. While most ancient inscriptions celebrate military victories or religious devotion, this one documented civil engineering: canals dug, rivers redirected, farmland protected from seasonal flooding.

The ceremony marking the Gomati canal's completion involved Brahmin priests and the gift of a thousand cows, a ritual scale that underscores how seriously the Tarumanagara court took its waterworks. Controlling rivers in the low-lying coastal plain of northern Java was not merely useful; it was an expression of royal authority. A king who could redirect a river demonstrated mastery over the natural world, the same kind of cosmic power that Indian political philosophy attributed to a chakravartin, a universal ruler. The inscription's careful recording of the canal's length, the project's duration, and the ceremonial details suggests Purnawarman wanted this achievement remembered alongside his other edicts carved into riverside boulders and cliff faces across western Java. Fifteen hundred years later, the floodplains he once engineered lie beneath one of the largest cities on Earth, but his stone still speaks.