Many the battles that were fought during the expansion of the Arab-Muslim empires after the time of the Prophet (S) were the same sort of battles that any other empire or state engages in to look after its political, financial or economic interests, although it is true that, as a side effect, it contributed to the spread of Islam by establishing a ruling class who was Muslim. So, from that angle, there is nothing special about them to make them jihad fi sabil Allah.
However, if someone was fighting in defence or for other selfless reasons, this could be considered jihad, just as it would be considered jihad fi sabil Allah today if I risked my life to defend someone who is under attack.
Perhaps for that reason, there is a dua in al-Sahifah al-Sajjadiyah where Imam Zayn al-Abidin (A) prays for the soldiers on the frontier who are defending the Muslim state against enemies.
Also, even in times of jihad with the Prophet (S), whether or not fighting was counted as jihad was according to intention. For instance, some people might have gone to war for glory or financial gain, and so this is not the same thing as risking their lives or enduring battle solely for the sake of Allah.