The major resources of Africa were gold and salt. Gold is important for the Europeans because they really want to become rich. Salt is important for the Europeans because they need to preserve their food, specifically, meat.
Mansa Musa's hajj caused Arabic and Islam to spread all across Africa greatly. Also, he gave away a lot of gold during his trip, which made the value of gold decrease in the near future. The travel of his hajj was very difficult because it was mostly done in the Sahara desert. He brought over 60,000 people with him, 12,000 slaves, and they were all holding lots of gold. He also brought many animals with him.
Islam and the Arabic language spread through West Africa because of Mansa Musa's hajj. He taught it, built universities, and supposedly built a new mosque every friday. Islam and Arabic were taught to people and since mosques were so easily accessible, many people went to them and converted to Islam.