The important achievements of the Kushites among the options provided are:
- The defeat of the Assyrian army
- The invention of one of the world's first alphabets
- The development of Africa's first iron-working city
(Note: While the information provided in the options seems accurate regarding Kush's historical context, the details concerning specific events, such as the defeat of the Assyrians, can vary depending on historical interpretations. However, the Kushites were known for their achievements in iron working and contributions to writing.)