What was the first Harappan seal to be discovered?

Seal of Pashupati Nath Seal of a bull Seal of a Unicorn Seal of a dancing girl

Seal of a bull

The first Harappan seal to be discovered was the seal which resembled that of a bull and hence was called the Bull Seal. Later, many more seals were excavated including those of bulls, Pashupatinath, a unicorn etc.