Well the +1 warrior movement makes sense from a historical standpoint. To my Knowledge Shaka was responsible for developing a tactic known as the horns of the bull or some such thing. His men would attack from the front but would also flank around like the horns, so his men would be attacking his enemy not only in front but from behind. This tactic continued to be used even when against the British troops, by the new Zulu king, Cetshwayo.
The Battle of Isandlwana on 22 January 1879 also demonstrated the Zulu's impi's movement over more advanced British riflemen. The Zulu impis covered 50 miles in 5 days whilst the British covered only 10 in days. You must take into an account that the Zulu force was also much larger, something like 20,000 men compared to the British force of under 5000, though only 1000 were properly trained regular British riflemen. The Zulu won the battle of Isandlwana. They defeated the force of 1000 British riflemen armed with modern breach loading Martini Henry Rifles and also some cannon. What mainly caused the british defeat was gunpowder blocking rifle barrels and of course running out of ammunition.
This loss shocked Britain, they weren't used to losing battles. They didn't lose to that runt Napolean so they weren't best pleased to lose a battle to what they considered to be a mass of black savages armed with only stabbing spears, clubs, old muskets and cowhide shields.
However the British regained some dignity when as the battle of Isandlwana was coming to a close. Cetshwayo sent forward 4500 Zulu impis to cut off any British escape. These troops were led by the king's younger brother who wanted to share in the success of the previous battle by winning one of his own and so they attacked the British base at Rorke's Drift crossing on the Tugela river. The British in this case claimed victory by managing to repel a force of 4500 impis with only 139 men.
Okay i know the game isnt so hot with history, so in the game i prospose that zulus cannot research anythin tht would outdate their "super impis" until they reach modern (:
Now, the next time you play civ and you are at the stage where you have tanks and the Zulu player only has impi warriors defending his cities. Don't be so harsh as to think he is a noob. I would prefer to think he is a person who only wants to try and rein act real historical events. SO I beg of you not to attack him with tanks. Use riflemen as this is more historically accurate and will no doubt, make his day.
Well in tht case i would be the noob lol