According to economic historian Angus Maddison in his book The World Economy: A Millennial Perspective, India had the world's largest economy during 0 BCE and 1000 BCE.
ɐkˈoːɹdɪŋ tʊ ˌiːkənˈɑːmɪk hɪstˈoːɹiən ˈæŋɡəs mˈædɪsən ɪn hɪz bˈʊk ðə wˈɜːld ɪkˈɑːnəmi: ɐ mɪlˈɛnɪəl pɚspˈɛktɪv, ˈɪndiə hæd ðə wˈɜːldz lˈɑːɹdʒɪst ɪkˈɑːnəmi dˈʊɹɹɪŋ zˈiəɹoʊ bˌiːsˌiːˈiː ænd wˈʌn θˈaʊzənd bˌiːsˌiːˈiː.