Prior to the arrival of German and Austrian Jews, there were already two relatively well established Jewish communities in Shanghai - the Sephardic Baghdadi Jews, numbering roughly 800, and the Ashkenazi Russian Jews, numbering roughly 4,000. Both communities, due to differences in religious practices, were relatively isolated from each other, except when it came to helping out the influx of Jewish refugees.
Between 1938 and 1939, nearly 23,000 destitute central European Jews arrived in Shanghai. The burden to look after them fell completely on the local Jewish communities.
On their arrival, they were often taken directly to the Embankment House which Sir Victor Sassoon, the owner, had already converted into a refugee shelter with a capacity to accommodate 2,500 people. They were able to stay there until they could find permanent lodging elsewhere.
Dvir Bar-Gal, a journalist and Shanghai Jewish historian said, “to many [Jewish Refugees], the Embarkment Building was their first roof in the new town, until they could find their way out of there to other housing or move to other shelters throughout the Hongkou district.” 
The Embarkment Building was a massive luxurious, curing edifice that extended a quarter of a mile in length. It was the largest building on the coast of China.
The building was ultimately taken over by the government and turned into government housing. Three floors were added in the 1980s.
Dvir Bar-Gal, a journalist and Shanghai Jewish historian said, “to many (Jewish Refugees), the Embarkment Building was their first roof in the new town, until they could find their way out of there to other housing or move to other shelters throughout the Hongkou district.” (2010)
Sir Victor Sassoon also endowed a Rehabilitation Fund which provided loans to the refugees to start businesses so that they could become self-sufficient, and help to hire other refugees.
On October 19th, 1938 the wealthy Baghdadi Jews established the Committee for the Assistance of European Jewish Refugees in Shanghai to provide the much-needed food, housing, education, and medical care to those who could not help themselves. By July 1939, assistance from the American Jewish Joint Distribution Committee arrived as well, in the form of volunteers and financial aid.
Refugee life in Shanghai was tough. Harsh weather and inadequate sewage contributed to a high illness and death rate. The Sino-Japanese War and Japanese occupation completely destroyed the economy and wiped out nearly all employment opportunities. The men had even more difficult time adjusting because they mostly came from well-educated and well-respected professional backgrounds; the harsh reality of living on third-party aid was extremely degrading and hard to accept. Interaction with Chinese neighbours, themselves oppressed by the Japanese, was made even more strenuous due to the language barrier and fighting over extremely limited resources.
By end of 1939, the Jewish communities took care of the basic needs of almost 16,000 refugees.
On 7th December, 1941 Japan attacked Pearl Harbour and officially entered the Second World War. The Japanese took over the foreign concessions and now took control of the entire Shanghai. They ended all foreign aid, including that of the American Jewish Community.
The Baghdadi Jews were sent to work camps on the outskirts of Shanghai where they were over-worked, underfed and housed in extremely cramped accommodations. The Russian Jews, together with other European residents in Shanghai, not only were sent to work camps but were also required to wear armbands to identify themselves and had their movements being monitored and restricted.
The large mansions owned by the Baghdadis were now occupied by the Japanese troops. Their assets were confiscated and their businesses came to a complete halt. Many Baghdadis resorted to selling their valuables to sustain a living. The Jewish community in Shanghai completely fell apart.
By February 1943, the Japanese established the Shanghai Ghetto (上海难民营), officially called “Restricted Sector for Stateless Refugees (无国籍难民限定地区)”, and ordered all Jews who arrived after 1937 to move both their residence and business there. The refugees were kept in this area until the end of the Second World War.
With the ensuing Chinese civil war and the establishment of the State of Israel in 1948, almost all Jews who arrived in China following the First Opium War left the country.