纪录片《大英博物馆世界简史》 060基尔瓦陶器碎片（7）（在线收听）

All this trade made Kilwa very rich, but it changed it in more than material ways, because this was a trade with a distinct and unusual annual rhythm. Because the ocean winds blow north-east for one half of the year and southwest for the other, merchants from the Gulf and India usually had to spend months waiting for the wind home. And in these months they inevitably mixed closely with the local African community, and transformed it. In due course, thanks to these Arab traders, the coastal towns were converted to Islam, and Arabic and Persian words were absorbed into the local Bantu language to create a new lingua franca - Swahili. The result was a remarkable cultural community running through the coastal cities from Somalia to Tanzania, from Mogadishu to Kilwa - a kind of Swahili strip, if you like, Islamic in faith and cosmopolitan in outlook. But the core of Swahili culture remains unquestionably African. As the historian Bertrum Mapunda explains:

"We know that when these immigrants came to East Africa they came here because there were attractions here. And one of the attractions was trade. It was because of these local people who had attracted them, that the Swahili culture later on was born. So it's not true to say that this is something which was bought from outside, when we know that there were local people here who had contributed the starting point, and from there, then people from outside came and were interested."

贸易让基尔瓦富裕起来，但它所带来的并不仅仅是物质上的改变。因为海上东北风与西南风各有半年，贸易通常以年为单位进行，来自波斯湾和印度的商人常常要滞留数月才能等到归途的顺风。在这些日子里，他们不可避免地与当地人密切接触并逐渐影响对方。由于阿拉伯商人的潜移默化，从某一时刻起，这些海滨城市开始信仰伊斯兰教，当地的班图语吸收了阿拉伯语和波斯语的词汇，产生了一种新的通用语斯瓦希里语。从索马里到坦桑尼亚，从摩加迪沙到基尔瓦，这些海滨城市组成了一条斯瓦希里文化带，居民都信仰伊斯兰教，外表也是内外合璧。但毫无疑问，非洲文化仍然是斯瓦希里的文化核心。历史学教授马彭达解释道：

我们知道，人们移民东非的一大诱因便是贸易。当地居民吸引了外来移民，之后才有斯瓦希里文化的诞生。它并非“舶来品”，而是当地居民奠定下基础，外来人口再渐次加入。