The historical sequence of the specimens was interpreted to indicate an evolution in the level of stylistic refinement over several centuries, and they concluded that the Brahmi script may have arisen out of "mercantile involvement" and that the growth of trade networks in Sri Lanka was correlated with its first appearance in the area.[31] Salomon in his 1998 review states that the Anuradhapura inscriptions support the theory that Brahmi existed in South Asia before the Mauryan times, with studies favoring the 4th century BCE, but some doubts remain whether the inscriptions might be intrusive into the potsherds from a later date.[30] Indologist Harry Falk has argued that the Edicts of Ashoka represent an older stage of Brahmi, whereas certain paleographic features of even the earliest Anuradhapura inscriptions are likely to be later, and so these potsherds may date from after 250 BCE.[32]