किस प्राचीन यूनानी इतिहासकार और राजदूत ने अपनी पुस्तक 'इंडिका' में भारतीय समाज को सात अलग-अलग वर्गों में वर्गीकृत किया था?

In which Major Rock Edict did Emperor Ashoka mention the Egyptian King Ptolemy II Philadelphus as his contemporary?

Which was the capital city of the Mauryan Empire?

The Later Mauryan rulers following Ashoka were comparatively weak. Which of the following was a major consequence of their inability to maintain effective central control over the vast empire?